Mahiro the Own-Home Security Guard

Mahiro the Own-Home Security Guard (まひろと特別自宅警備, Mahiro To Tokubetsu Jitaku Keibi) is Chapter 10 of Onimai: I'm Now Your Sister. It was originally published on Pixiv on November 27, 2017.

Summary
Mihari comes down with a sudden cold, so Mahiro takes it upon herself to take care of her.

Plot
Mahiro sits at her computer and her stomach growls. She notes that lunch sure is taking awhile and that they are usually done eating by now. Fed up with waiting, Mahiro storms off to Mihari's room saying that she'd better not be sleeping. Mahiro opens Mihari's door and begins to asks what's up with lunch, but stops when she sees that Mihari is in bed, sick with a fever and a washcloth on her forehead.

Mahiro thinks that Mihari has gotten her period, which causes Mihari to bolt upright and call Mahiro a dummy for thinking that. She confirms that she is sick before feeling disoriented and laying back down. Mahiro apologizes, and Mihari says that its okay as she took some medicine and now just needs to rest. She tells Mahiro that there is some ramen in the cupboard, and that she'll have to settle with that for today. Mahiro feels uneasy about leaving a sick Mihari alone.

Mahiro makes the ramen, but sits there unable to eat. She thinks to herself how Mihari has been staying up later doing her research reports, how she's barely been sleeping, and doing all the housework on top of that. In contrast, Mahiro hasn't been doing anything to help out. Mahiro thinks of herself as being the worst, and the most ungrateful piece of trash to walk the earth.

Mahiro clenches her first and decides that she can do one day's worth of housework, delcaring it to be a piece a cake. She says that this too is the duty of the "own home security guard", and decides to show Mihari what an admirable older brother is capable of. The top on the ramen suddenly pops off, and Mahiro eats it, realizing that she left them too long.

First, Mahiro attempts to do the laundry. Having never done so, she is confused by what to do with the bleach, fabric softener, delicate wash, and fragrance free, and decides that they must all go in the same place.

She then decides to vacuum, knowing how to do that at the very least.

While doing so, Mahiro realizes that Mihari hasn't eaten anything yet. She knows that the best things in this situation is rice porridge, but then realizes that she has no idea how to make it.

Desperate for help, she calls up Kaede who is happy to hear from Mahiro. She asks what's up, with school having just let out. Mahiro tells her that she is trying to make rice porridge, and Kaede tells her that it is easy. Kaede then deduces that Mihari is sick, and asks if Mahiro wants her to come over and help. Mahiro is initially happy at this, but changes her mind and declines saying that she can't handle that. She ultimately does her best and leaves it to simmer for half an hour.

Mahiro relaxes, noting that she never thought that cooking would be this easy, and that making rice porridge is barely any harder than making ramen. She decides that she next has to tackle cleaning the bath, which gives her another idea.

Mahiro brings the porridge to Mihari who is extremely surprised the Mahiro made food for her. Mahiro confirms this, but can't promise that its any good. Mihari suddenly bursts into tears. Mahiro asks her what is going on, and Mihari mentions how moved she is by the fact that Mahiro cooked for her. Mahiro dismisses her feelings and tells her to eat up, which Mihari agrees to. Mihari notes that the food is flavorless but that she is still so happy. Mahiro realizes that she forgot to add the salt.

Mihari finishes all of the porridge and notes that she is feeling a little better now. Mahiro says that is good and tells Mihari to strip, which leaves Mihari confused; Mahiro intends to give Mihari a sponge bath.

Mihari strips as requested, keeping herself wrapped in a towel. She tells Mahiro that she is a brute for doing something like this to someone who can't resist, but Mahiro tells her to call her whatever she likes. She begins by washing Mihari's back, saying that she is getting back at Mihari for all the times she embarrassed her. She eventually hands Mihari the washcloth, telling her that she can do the front on her own. Mihari grabs it saying that she obviously can, and begins to do so.

When Mihari finishes and redresses, Mahiro tucks her in all nice and warm and tells her to sleep tight. Mihari smiles and thanks Mahiro for everything, though Mahiro brushes it off again.

The next morning, Mihari is fully recovered and goes to tackle the laundry backlog. Mahiro knows that she won't find one and that she'll cry again. This does indeed happen, revealing that Mahiro's efforts to do the laundry ruined all of Mihari's nice clothes. Mihari cries and turns to Mahiro, who immediately apologizes. Instead of yelling however, Mihari just sighs and tells Mahiro that she won't make a good housewife at this rate. Mahiro, shocked at that statement, insists that she doesn't want to be one.

A few days later, Mihari starts feeling bad again. Mahiro asks her if she's sick again, but Mihari tells her that it really is period cramps this time.

Characters

 * Mahiro Oyama
 * Mihari Oyama
 * Kaede Hozuki
 * Momiji Hozuki

Trivia

 * First appearance of Momiji Hozuki.