Mahiro, the Sun, and the Northern Wind

Mahiro, the Sun, and the Northern Wind (まひろと北風と太陽, Mahiro To Kitakaze To Taiyō) is Chapter 53 of Onimai: I'm Now Your Sister!. It was originally published on Pixiv on June 26, 2021.

Summary
Mahiro and her classmates deal with the perils of an extremely hot day combined with an overpowered air conditioner.

Plot
The sun is shining brightly, and as Mahiro walks to school she notes that she is melting from the heat. Kaede notes that the end of the rainy season is always tough, and points out that they are just not used to the heat yet. Momij tells Mahiro to hang in there, as they are turning on the AC today. Kaede is is disbelief that that only put the AC in when she was in her first year of middle school. Momiji is shocked at this statement, and asks how all "you old-timers" survived. Mahiro feels stabbed by this statement, as she's technically lumped in since she dealt with a lack of AC personally during her entire first time attending middle school as a boy.

In Class 2-B, Mahiro sweats, cries, and wonders why the AC isn't on yet. Nayuta points out that class hasn't started yet, and Momiji tells her to just wait a little longer. Asahi says that she's fine as is, leading Mahiro to cringe at the fact that Asahi is even immune to the heat. Miyo on the other hand is still wearing her sweater, causing her to sweat more than anyone else. Mahiro tells her that she has to take it off, with Momiji pointing out that she'll die in this heat. Miyo refuses, pointing out that the sweat will make her shirt see-through. She says that she is only wearing a shirt and will stand out too much. Mahiro realizes this and apologizes, realizing that she was inconsiderate, again.

Mahiro realizes that it's not just everyone else that's the problem, as girls don't want people seeing their bras. Mahiro thinks to herself that it is so much easier being a boy in this heat, as they can just get away with just wearing a tee-shirt.

While saying this, Mahiro's eyes look in the direction of Yuta and Minato who are also sweating, wearing tee-shirts, and fanning to keep themselves cool. When they see Mahiro staring at them, they panic and try to cover themselves up out of embarrassment. Satsuki and Minori block the view and claim to the boys that there is nothing to see here, much to their shock. The girls then realize that this time it was the reverse and apologize, much to the boys' relief. Mahiro in turn is equally amazed that it didn't do the same way this time.

Mari finally comes into the class and turns on the AC much to everyone's relief. Mahiro slumps forward at her desk in relief, noting that this is comfort. She notes that it's hard to be energetic in that heat and remarks that it's a good time to be alive.

Mahiro starts to notice though that it's a little too cold now, and starts to shiver and wonder why they got to face both extremes. Nemu notices this and wakes up to rummage through her bag. Mahiro is intrigued and sees Nemu put on a cardigan sweater before going back to sleep. Mahiro is amazed at Nemu's forethought, deciding that she'll have to bring hers tomorrow.

Nayuta sees Mahiro rubbing her hands together, and offers Mahiro her own cardigan, saying she can borrow it if she wants. Mahiro calls Nayuta her savior for always being there when she's needed and thanks her. Nayuta is more than happy to do so.

As the bell rings, Mahiro notes to Nayuta that she really saved her there, but notices that Nayuta is now shivering instead. Mahiro feels bad and without a thought gives the cardigan back, telling Nayuta that she should've said that she was cold. Miyo notes to Nayuta that she's always so reserved, and Mahiro tells her that she doesn't need to hold back about this stuff.

Asahi is amazed that they're cold and tells them to leave it to her. Momiji hugs Asahi and confirms that Asahi is very warm. Mahiro and Nayuta both confirm this, with Nayuta saying that children have higher temperatures. Asahi tells them to grab on, and the sight caused Miyo to get aroused.

Seeing Mahiro, Momiji, and Nayuta snuggled up to Asahi for warmth caused Miyo to get even more aroused, calling it an excessive bounty. She notes that she's starting to feel a little warm and decides to take off her cardigan as well, much to Mahiro's shock. Miyo takes off her cardigan in relief, but as she said her oversized bust and bra is visible through her shirt. Mahiro, Momiji, Asahi, and Nayuta stop what there doing and point this out to Miyo as she gets stares from the entire class. Miyo snaps back to reality and covers herself back up in horror.

She cringes and notes that she forgot herself. Momiji suggests that she could ask Kaede for her, about how to prevent see-through. Mahiro thinks that she'd better ask as well. Meanwhile, Satsuki criticizes the boys again for looking at Miyo, much to their fear.

As Momiji tells Miyo that she's really something, Asahi suddenly sneezes. In the Nurse's Office, Asahi wears a surgical mask and explains that she had a cold the entire time. Momiji realizes that Asahi was running a fever, and that's why she was so warm. Mahiro is amazed that even Asahi catches colds.

It is revealed that Nemu was fanned by Nodoka when it was still hot in the classroom.

Characters

 * Mahiro Oyama
 * Kaede Hozuki
 * Momiji Hozuki
 * Asahi Ōka
 * Miyo Murosaki
 * Nayuta Tenkawa
 * Minato Senkawa
 * Yuta Sakurada
 * Satsuki Tadaka
 * Minori Shiina
 * Mari Nishinomiya
 * Nemu Fujimi
 * Nodoka Fushimi

Trivia

 * It is revealed in this chapter that the middle school didn't install an air conditioner until Kaede was in her first year, meaning that Mahiro had to deal with hot days without one during her entire time attending middle school the first time as a boy.
 * Mahiro is still trying to be more considerate by not looking at her friends, first having done so in "Mahiro and the School Physical" and in "Mahiro and the Seasonal Attire".
 * As mentioned in the chapter, in Japan there is a stereotype that "idiots can't catch colds".