Mahiro is Me and Mihari is Me

Mahiro is Me and Mihari is Me (まひろわたしでみはりわたしで, Mahiro Watashi De Mihari Watashi De) is a special chapter of Onimai! I'm Now Your Sister. It was originally published in EX Special 2 which was released on December 30, 2019.

Summary
A bizarre accident causes Mahiro and Mihari to switch bodies.

Plot
Mahiro and Mihari look at each other with shocked expressions. They realize that they've swapped bodies, much to their horror.

Sitting at a table, Mihari wonders how this happened. Mahiro thinks to herself how Mihari was getting a box from up high and asked for help. Mahiro offered her help by getting on all fours and letting Mihari climb on top of her. Mihari then lost her balance, and headbutted Mahiro from behind, causing the swap.

Mihari cringes, calling that explanation so unscientific. She begins to try and figure it out, saying something about neuron signals, but Mahiro tells her to calm down. She points out that this happens a lot in manga, and that they just need to smack their heads together again to go back to normal. Mahiro grabs Mihari's head and decides to do it, telling Mihari to get ready.

Mihari tells Mahiro to hold on, saying that logically this is an amazing experience. She suggests that since they have the chance, she needs to do all sorts of experiments. Mahiro groans, noting that Mihari is in her research mode and calls it so like her, while crossing her arms.

When Mahiro crosses her arms, she squshes something, and realizes that she felt Mihari's bust, and begins to swuish it with both hands. Mihari reacts in horror and demands to know what Mahiro is doing. Mahiro apologizes, saying that they were just shockingly soft and squishy. Mihari angrily bans Mahiro from touching her body, saying that the bathroom is especially off limits. Mahiro notes that that's kind of harsh, but notes that Mihari would be embarrassed since she's at that age. Mahiro says that she'll do her best, and Mihari decides to do something.

This something turns out to be a fashion show where Mihari models several outfits in Mahiro's body, all the while posing cutely. Mahiro claps, noting that it's a smorgasbord. She suddenly comes to her senses and realizes that Mihari is just joking around. Mihari giggles, and notes that these clothes look so good on Mahiro's body unlike hers. Mahiro points out that she thinks that they'd look good on Mihari's body as well, but Mihari cringes and insist that there's no way that they do. Mahiro decides that since they have this chance, she'll let Mihari see them from a different angle and says to bring out the cute stuff while stripping off Mihari's lab coat. Mihari says that its okay and begs Mahiro to stop stripping. All of a sudden, the doorbell rings, and Mahiro wonders if it is the mail.

It turns out to be Kaede who says hello to both of them. Mihari cinges, as she forgot that she promised she'd keep an eye on her studying. Mahiro is overjoyed to see Kaede and hugs her as she would anyday while saying welcome. Kaede is confused by "Mihari's" strange behavior and asks her what's wrong. Mahiro realizes her mistake and says that its nothing, but Kaede still senses that something's off. She asks "Mahiro" if her big sister is okay, and Mihari laughs a bit at the situation.

Kaede says that math is up first, and Mahiro panics, as she's no good with high school math. Mihari silently tells Mahiro to follow her lead. When Kaede apologizes and asks what she needs to do for one, Mahiro says that she wonders. Mihari suggests that maybe you use a certain formula, and Mahiro confirms it to be the case. Kaede is shocked and tells Mahiro "good job", saying that that's Mihari's little sister for her. Mahiro cringes a bit while Mihari giggles again.

Mahiro sighs inside and drinks some water noting that this is thirsty work. Mahiro then panics upon finishing the water. Kaede asks what's up, but Mahiro tells her not to worry, insisting that they go onto the next one. Kaede calls "Mihari" a Spartan, while Mahiro starts to fidget and notes that this is bad. Mihari is left confused by this.

One hour later, Kaede stretches and notes that that should be it for math. She then notices "Mihari" slumped over the table shaking and groaning. Kaede notes that "Mihari" isn't feeling good and that she thought that something was off, though "Mihari" insists that she's fine. Kaede tells her to get some rest, and says that she'll make her just the thing for this as thanks for this afternoon, which "Mihari" agrees to".

As Kaede goes into the kitchen to make something light, Mihari asks Mahiro if she's okay and if she's actually having trouble. Mahiro says that she said it's nothing, but Mihari notes that it doesn't look like it. Mihari wonders if it was from the body swap and insists that they swap back right now. Mahiro warns Mihari that they can't, saying that something bad will happen to her, but Mihari insists that it's better than something bad happening to her onii-chan. She grabs Mahiro's head and notes that they just need to hit heads. Mahiro begs Mihari to listen to her, but Mihari goes through with it and headbutts Mahiro.

As the two recover from the headbutting, they realize that they successfully switched back. Mihari notes that she's thankful, but then suddenly feels a terrifying sensation. She is horrified that this was what Mahiro was talking about and lets out a scream.

In the kitchen, Kaede turns off the sink and brings out the dish of risotto that she made. She becomes shocked when she sees that Mihari wet herself, due to Mahiro not using the bathroom. Mahiro gets an embarrassed expression on her face, while Mihari cries and tells them not to look at her.

Kaede realizes that Mihari is super sick and tells her that it's okay, saying that they should head to the bathroom. Mihari is silent, while Mahiro makes a prayer sign and silently apologizes to Mihari for this.

Later, Mihari sits on the couch with Mahiro, still sad. She tells Mahiro that she's not mad at her, as it is her fault for banning the toilet. Mahiro sighs a bit, but comforts Mihari all the same.

Later, Kaede thinks to herself that this incident proves that Mahiro and Mihari are definitely sisters.

Characters

 * Mahiro Oyama
 * Mihari Oyama
 * Kaede Hozuki

Trivia

 * Kaede references the time that Mahiro wet herself in the bathroom of the movie theater in "Mahiro and Kaede's Secret".
 * Due to this chapter being published exclusively in EX Special 2, it has not received an official English translation or release, though an English fan translation is available for purchase at DLSite alongside the Japanese release.