Mahiro's Melancholy Day

Mahiro's Melancholy Day (まひろと憂鬱な日, Mahiro To Yūutsu Na Hi) is Chapter 5 of Onimai: I'm Now Your Sister. It was originally published on Pixiv on June 24, 2017.

Summary
Mahiro starts feeling bad

Plot
Mahiro sits on her bed breading her hair into two long side braids then holds the ends to the front of her face to make it playfully make it look like she has a moustache. She then realizes what she's doing an stops in shock wondering why she was doing that.

Mihari comes in and notices what Mahiro did with her hair and notes that it is super cute. Mahiro is shocked by Mihari's sudden appearance and remarks that it has been so warm out that she thought she'd cool down by putting her hair up. She notes that she tried a large variety of hairstyles including long pigtails, side pigtails, and a bun and eventually got carried away. Mihari notes how talented Mahiro is and tells her that she'd look great with a ribbon. Mahiro cheers for a minute while Mihari starts to put one in her hair, then comes to her senses and tells Mihari to knock it off.

Mahiro collapses on the bed remarking that she is scaring herself, as she is getting way too good at doing things like girls do. Mihari even notes that Mahiro is sitting like a girl, which scares Mahiro even further. Mahiro lets out a few tears noting that this sucks, then makes a complete turn and declares that she'll just have to capture her lost masculinity.

Mahiro decides to work out and get buff and lies on the bed. She starts trembling, and Mihari asks if that is supposed to be Mahiro's attempt at doing a sit-up. She tells Mahiro that if she's going to work out to be serious about it. Mahiro remarks that she thinks she strained something, to which Mihari calls her a dummy. Mahiro remarks that she's serious and that she feels kind of sick. Mihari asks Mahiro if she's okay, before Mahiro collapses on the bed much to Mihari's shock.

Some time later, Mahiro wakes up saying that it's gotten a little better. Mihari cries saying that that is a relief. Mahiro tells Mihari not to cry saying that it's not a big deal, but Mihari is insistent. Mahiro wonder what happened, as she doesn't think that she caught a cold or anything and asks if it could be a side effect of the drug that Mihari gave her. Mihari thinks to herself that she was pretty careful about safety precautions, and that it had been a month since the change without any issues so far.

Mihari suddenly realizes that it has been exactly a month, and asks Mahiro if she has any other symptoms like her breasts feeling swollen. Mahiro says that they are now that Mihari mentioned it. Mihari tries to explain what is going on, but Mahiro feels another sharp pain in her stomach and excuses herself to go to the bathroom. Mihari tries to tell Mahiro to wait, but changes her mind and instead tells Mahiro to brace herself, which leaves Mahiro confused.

Mahiro sits down on the toilet and wonders why Mihari has gotten all worked up about her using the restroom, but looks down and sees what she was trying to say. Mahiro is experiencing her first period and lets out a piercing scream.

Some time later, Mahiro lays under the covers shaking over the fact that there was lots of blood. Mihari tells her to just get comfortable as it's easier when you're warm and cozy.

Mihari then suggest Mahiro enjoy a frozen dinner of red beans and rice, to which Mahiro questions her on why she has that in the first place.

Mahiro then eats the dinner, wondering if she is ever going to return to normal.

Characters

 * Mahiro Oyama
 * Mihari Oyama

Trivia

 * This chapter and "Mahiro, Even On Heavy Days" are said to take place exactly one month after the events of "Mahiro's Confusing New Body".
 * As noted in the chapter, red beans and rice is a traditional celebratory mean eaten by Japanese girls after their first period.