Houkago Shounen Hanako-kun

Houkago Shounen Hanako-kun (放課後少年花子くん/After-School Boy Hanako-kun) is a spinoff manga series written and illustrated by AidaIro.

The manga is published in the PFantapy (Pファンタピー) which is hosted on pixiv comic, and previously updated once a month. The most recent chapter was released in June 2019, and the date for the next update will be announced on the GFantasy twitter.

Fifteen chapters were collected and published in a volume of the same title on August 27, 2019 (the same day as Volume 11's release).

Plot Summary
The spinoff depicts short stories about the daily lives of the characters outside of the main storyline.

Day 2: Game of Kings (2日目：王様ゲーム)
Hanako, Nene, Kou, Tsuchigomori, and a Mokke are playing the Game of Kings in the toilet. The game involves drawing lots (with one labelled "king" and the rest with numbers), and the person who draws "king" can order those with numbers to do anything they wish. However, unlike ordinary games, the king's orders will absolutely be carried out as they are using mysterious tools from the far shore for their lots. Teru suddenly walks in. Although Kou says that Teru isn't here to exorcise anyone, Hanako tries to get Tsuchigomori to kick Teru out (to no avail, since Teru threatens to report Tsuchigomori for being in the female toilet).
 * Round 1: Hanako is king, and orders 3 (Mokke) and 4 (Tsuchigomori) to dance flamenco.
 * Round 2: Tsuchigomori is king. He tries to use this to drop out of the game but Hanako bans it, so Tsuchigomori orders 1 (Hanako) to do kanji dictation exercises.
 * Round 3: The Mokke is king. Believing that the Mokke's order would definitely be something cute, she asks if it wants luxury sweets, but the Mokke says it will kill everyone and become one of the Seven Mysteries. Hanako (still doing dictation) says it's not an order, so the Mokke asks for sweets instead.
 * Round 4: Nene is king, and orders 1 to kabedon her and declare their love… but 1 turns out to be the Mokke, rather than Teru as she'd hoped.
 * Round 5: Kou is king, and decides to help Nene since he can see Nene and Teru's numbers (1 and 3). However, he mistakenly says 1 and 4 instead, causing the Mokke to kabedon Nene again.
 * Round 6: Teru is king, causing all the supernaturals to freak out. Teru says he's only here to play a game, but then tells 1 (Hanako) and 4 (Tsuchigomori) to fight him to the death.

Day 3: Mokke Be Ambitious. (3日目：もっけの野望 Mokke be ambitious.)
Nene happily arrives at the toilet one day to find Hanako buried under a hill of Mokke. After rescuing him, Nene asks the Mokke if Hanako had been bullying them, to Hanako's protests that he's the one being bullied instead. The Mokke answer that they weren't bullying Hanako… only trying to kill him so that they can become one of the Seven Mysteries. Hanako admits that there are vacancies in the Seven Mysteries now, but says the Mokke would definitely misuse it (which the Mokke deny while carrying weapons).

Hanako holds a job interview for the Mokke, with Nene taking notes as his assistant. The Mokke, now wearing business ties, fail the interview after revealing that their ambition is to destroy the world. They explain that they won't kill anyone, only destroy the school to build a crop field of sweets in its place, and put all the people to work in the field. Hanako tells them to give up, while Nene suggests that they get someone to make sweets for them instead. She mentions that Tsuchigomori had made hard candy in class.

Tsuchigomori hears the ground rumble, which is revealed to be a rampage of Mokke, who only release him after he makes tens of thousands of candies for them.

Day 4: Table-turning (4日目：コックリさん)
Akane proposes to play "Kokkuri-san" (similar to a table-turning seance) with Aoi, Nene, and Lemon. Though Akane is uninterested in the occult, Aoi showed interest in "Kokkuri-san" half a year ago, so Akane has been making preparations to summon the best low-level spirit possible, using highest-quality calligraphy paper and ink with his blood mixed in. They begin the ritual while Nene worries whether a ferocious spirit might come. Suddenly, a burst of wind heralds the appearance of a spirit… which turns out to be a Mokke. Nene is relieved, but wonders what kind of answers the Mokke will give. Lemon stars by asking about tomorrow's weather. The Mokke moves the 10-yen coin to spell "a-me", which Nene realises means "sweets" (飴) but the rest interpret as "rain" (雨).

Akane then asks the real question: who is the person that he likes? The Mokke starts with "a" again, but then sneezes, causing the coin to bounce and spell "re-mo-n" or Lemon. Akane frantically denies liking Lemon, beating him up with his bat, while Aoi wishes them happiness as she leaves.

Meanwhile, the Mokke escapes with a bottle of ink (presumably the one with Akane's blood mixed in).

Day 5: Afterschool Broadcasting Room (5日目：放課後の放送室)
Natsuhiko introduces himself and his plan to seduce Sakura with a love potion for one day. He puts it in a cup of tea and offers it to her, but Tsukasa asks if he can have it instead and Sakura agrees. Natsuhiko tries to stop Tsukasa from drinking it, but Tsukasa misunderstands this as Natsuhiko wanting to drink it himself and smashes the cup into his face. Natsuhiko faceplants onto the sofa. Sakura checks if he's alright, and Natsuhiko proclaims the beauty of… himself reflected in Sakura's eyes.

The love potion's effects wear off a day later.

Day 6: Afterschool Student Union Room (6日目：放課後の生徒会室)
Akane is being hung upside down in the Student Union room by Teru's bracelet chain. Teru claims that it's Akane's job, and that he has nothing against Akane personally, but supernaturals are like cockroaches to him. By relieving the stress of not being able exterminate "half-cockroaches" like Akane who still appear human, Teru's work efficiency increases, which he says is Akane's job as vice-president. Teru eventually releases Akane, but promptly makes him fall into a pit when Akane questions the reason for Teru's popularity. Teru smiles, and completes all the Student Union work at amazing speed afterwards.

It's shown that Teru tolerates the Mokke because his younger sister likes them.

Day 7: The Summer Demon ~Toilet Bound Girl Hanako-san~ (7日目：夏の魔物〜地縛少女花子さん〜)
Hanako has been turned into a girl by a strange device, which will last for about a day since she defeated the device. Yashiro excitedly suggests doing girl-like things, starting with an outfit change to a bobbed cut and red skirt (as in the original Hanako-san legend). She then styles their hair to match, and Hanako has just decided to show it to someone else when Kou arrives. He's confused, initially assuming that the unknown girl is Hanako's elder sister until they explain the situation. Hanako then flirts with him, asking if he finds her cute, but Kou says no as she's not his type. Hanako is devastated as Yashiro consoles her.

Day 8: The Summer Demon ~Reprise~ (8日目：夏の魔物〜再来〜)
Tsukasa finds the strange device buried, and accidentally ends up changing Sakura into a boy. The device is defeated yet again. Tsukasa apologises, while Natsuhiko is in shock. Sakura is unbothered, merely borrowing and changing into a male uniform from Natsuhiko. Natsuhiko realises Sakura is more handsome than him now, and asks Tsukasa to change Sakura back to no avail. Sakura says that he doesn't care about Natsuhiko's gender (which Natsuhiko predictably interprets to mean that Sakura loves him no matter what). Natsuhiko declares that Sakura is his important lady either way, and since Sakura has become a man, he puts on the uniform dress to become a girl. Unimpressed, Sakura slaps him with a book.

Day 9: True Of Mokke (9日目：トゥルー・オブ・もっけ)
Nene has turned into a Mokke. She doesn't remember how it happened, and the other Mokke greet her as a newcomer. The Elder Mokke arrives on a palanquin, saying that it knows the truth of the universe and will show it to Nene. Nene is led beneath the school to see a large wall painting depicting the Mokke's history. When the Mokke gather and transform, they usually return to their original form, but sometimes stay in the transformed state and end up forgetting that they are Mokke. Therefore, the Elder Mokke says that everything in the world is Mokke. Mokke are the basis of everything, like protein, and even the Seven Mysteries were once Mokke. The Elder Mokke reassures Nene that she has merely returned to being Mokke, while the other Mokke welcome her back, but Nene denies this and flees. However, the Mokke stop her, declaring that the world was once Mokke and will eventually return to being Mokke, surrounding her as they chant "Mokke! Mokke! Mokke!".

Hanako calls Nene's name. It's revealed that Nene is asleep at her classroom desk with a Mokke brainwashing her, and Hanako tells it to stop.

Day 11: Supernatural Cold (11日目：怪異風邪)
Hanako is in the infirmary, having caught a cold. Tsuchigomori and Yako are also ill, and Tsuchigomori tells Nene about the supernatural cold. It only affects supernaturals, and aside from the usual cold symptoms, each supernatural's characteristics also become more easily visible. Being a ghost, Hanako is more transparent than usual, while Tsuchigomori is showing his inhuman characteristics like pointed ears and teeth (which he hides beneath earmuffs and a cold mask). Like the common cold, it's cured by resting. However, Hanako sits up suddenly, exclaiming that it's been decades since he caught a cold, so he's going to show Kou. Nene runs after him, only to find that Kou has thoroughly electrocuted Hanako, as he hadn't known about the cold, and thought that Hanako had finally revealed his true nature by flying at him so suddenly. Hanako hears Nene calling him as his eyes drift closed, and says that he's happy that she's worrying over him… while hugging a fire extinguisher that he's mistaken for Nene's leg. While Kou tells Nene to calm down, the Mokke arrive, having waited for the Seven Mysteries' moment of weakness, and pile onto Hanako to kill him.

Back at the infirmary, the Mokke have now all caught the cold from Hanako. Nene and Kou take care of them, while Hanako has recovered completely after transferring his cold.

Day 12: Mitsuba's Epic Friend Operation (12日目：ミツバの友達大作戦)
In the broadcasting room, Mitsuba obsesses over wanting friends. Natsuhiko tells Sakura that he's been like this since yesterday, after seeing a magazine article about activities to do with friends over the summer. Since Mitsuba can't befriend normal humans who can't see him, Natsuhiko offers to become friends with Mitsuba, but Mitsuba runs over to Sakura instead, begging her to spread a rumour that will allow him to make friends. Sakura tells him to look for a simpler option as the rumours are a last resort, but Mitsuba finds the Mokke somewhat terrifying, and vehemently rejects being friends with Kou when Sakura suggests it.

Mitsuba ends up telling Tsukasa that he wants to make friends. Tsukasa agrees… and begins to physically build Mitsuba a friend. Mitsuba frantically stops him and clarifies that he'd meant making friends with Tsukasa, to which Tsukasa agrees easily. However, he then attempts to make Mitsuba swallow fireworks (rather than playing with fireworks together as Mitsuba had envisioned), causing Mitsuba to unfriend him within 10 minutes.

Finally, Sakura consoles Mitsuba by saying that they can at least go along with whatever he'd wanted to do with friends. Sakura, Mitsuba, and Natsuhiko end up taking a group photo in a pose, with Tsukasa in one corner of the photo.

Day 13: Mokke In The House! (13日目：もっけが家にやってきた！)
At the Minamoto home, Tiara (Kou and Teru's 5 year old younger sister) introduces herself to the now-clean Mokke which previously caused the Mokke of the Dead incident, though it doesn't remember it. Tiara declares that the Mokke is her slave from now on, before bringing it to see Kou, who's cooking in the kitchen. Kou is happy to see Tiara, but glares at the Mokke for having caused the incident, and tells Tiara to keep a close eye on it. Tiara next brings the Mokke to Teru's bedroom, where he is taking an afternoon nap. However, Teru also glares at the Mokke on waking up, causing it to panic and run out of the house while Tiara hugs Teru. However, the Mokke quickly bumps into a giant insect-like monster, and is about to be attacked when a massive strike of electricity hits the monster from above. It's revealed to be from Tiara, who scolds the Mokke for going out on its own, after which they happily reunite and Tiara names it Minamoto Fairy.

It's noted that Tiara was named by the Minamoto father in the high anxiety surrounding the much-anticipated birth of a daughter. Though Tiara is young, she has great promise as her spiritual power exceeds even Teru's.

Trivia

 * At Tsuchigomori's orders, Hanako is shown writing on a box labelled "mikan" (mandarin), and the kanji he writes includes 寧 (from Nene's first name 寧々), 祓 (as in 祓い屋 or exorcist), and either 壁 or 璧.
 * In Day 2, Tsuchigomori is identified as a biology teacher.
 * In Akane's flashback on Day 4, Aoi is reading a book entitled "Occult Horror Reports" (オカルトホラー特集), while Akane is reading "Marriage Proposals to get an OK" (OKをもらうプロポーズ).
 * Though Kou's friends Yokoo and Satou were already mentioned by name in Chapter 4 (Misaki Stairs Part 1) of the main series, more is revealed about them in Day 10: Yokoo likes sports while Satou likes sweet things.
 * In Day 12, the magazine article's title is "Good Friends" with the G and F initials bolded, likely a reference to GFantasy, where the main series is published in.
 * Minamoto Tiara's full name (源てぃあら) is first revealed in Day 13.
 * In Day 14, the form teacher of Class 1-A (Nene's class) is finally named as Nagisa-sensei (ナギサ先生), who teaches social studies.