Mahiro Falls in Love

Mahiro Falls in Love (まひろとアバンチュール, Mahiro To Abanchyūru) is Chapter 11 of Onimai: I'm Now Your Sister. It was originally published on Pixiv on December 27, 2017.

Summary
Mahiro is sent out to buy groceries after losing a game, and ends up running into someone unexpected

Plot
Mahiro and Mihari are sitting on their living room couch. Mihari is doing something that is making Mahiro uncomfortable which she learns is Mahiro's weakness, and she does it again despite Mahiro's protests. Mahiro starts crying as she does it.

It is revealed that the two were playing a sumo-wrestling video game that Mihari has beaten Mahiro at multiple times, much to Mahiro's disappointment. For losing the game, Mahiro is given the household shopping list and has to go out to the grocery store near the train station to do the shopping, as per a deal that the two made. Mihari tells a scared Mahiro she can use the change to buy a snack if she wants, which makes Mahiro cringe over being treated like she's a little kid. Mahiro still decides to go, agreeing that a man can hardly go back on his word. Mahiro leaves house, still scared, and Mihari wishes her good luck.

As Mihari cleans dishes, she notes that Mahiro has gotten pretty used to going outside by now, and that she's been helping out around the house more since she got sick that one time. She decides that it's almost time to reintroduce Mahiro to society. She fantasizes that soon Mahiro will become a blushing bride and settle down, but then realizes that that won't likely happen.

Outside the store, Mahiro sees a large crowd of people and gets overwhelmed. She decides that she can handle the corner store, but not this place as there is too many people. Mahiro then buckles down and says that she has to as she's only just gained a scrap of the dignity that an older sibling deserves.

Soon after, an unfamiliar person taps Mahiro on the shoulder and asks her if she's okay, saying that she doesn't look so good. Mahiro sees that it appears to be a boy and gets a bit surprised as he doesn't know who this boy is. The boy feels Mahiro's forehead asking if she's running a fever, which surprises Mahiro even more. The boy tells Mahiro that if she's not feeling well that he can help her out. Mahiro is at a complete loss for words.

The two go into the store together and Mahiro apologizes for all the trouble. The boy says that it's no problem, as they are about the same age after all. Mahiro can feel her dignity crumbling away, as she was crying in front of a boy she doesn't even know. The boy mentions that he hates crowds as well.

The boy asks Mahiro what she needs, and Mahiro looks for the list. The boy reads off that the list contains pork, cabbage, and mushrooms, and asks Mahiro if she is making a hotpot. He asks Mahiro if they should go with the cheap stuff, but Mahiro has no clue. The boys suggest that they see how much money if left over first. Taking a look at a vegetable, the boy tells Mahiro that the best ones have a clear separation between green and white. Mahiro calls the boy a lifesaver, and the boy is surprised, thinking that that bit of information was common knowledge.

The two continue their shopping and Mahiro thinks to herself what a nice boy this is. A pair of unknown girls notice the two with one of them thinking that Mahiro and the boy are a couple, with the other one telling her not to talk about strangers like that, calling it rude. Mahiro overhears the conversation and gets concerned, then remembers that it is natural to assume that as she is a girl right now. She thinks to herself though that despite that there is no reason to assume that she's into boys now.

The boy notices Mahiro's expression and asks what's wrong. Mahiro takes a look at the boy's face and then starts to realize that she does sort of like it, now that she thinks about it. She then slams her head against the wall, much to the boy's surprise, telling herself that this can't be right.

The two leave the store and Mahiro struggles to keep a straight face, as she almost gave into her base female instincts. The boys tells Mahiro that they did it, and Mahiro thanks him for his help. Mahiro thinks to herself that there is something wrong with her, and that she needs to get away from this boy as soon as possible. She turns around and thanks the boy again before saying that she'll be okay from here.

The boy's phone starts to ring and he tells Mahiro to wait for a second. Answering the phone, the boy talks to someone that they know saying that they are just outside the store with a friend. The mention of being "a friend" leaves Mahiro puzzled.

The person in question notices the boy and calls out to him, calling him Momiji. Mahiro turns towards the voice and notices that it is Kaede, who is equally surprised that Mahiro is the friend the Momiji mentioned. Kaede asks Momiji when the two of them became friends, and Momiji asks Mahiro how he knows his older sister. Mahiro is shocked that Kaede is Momiji's older sister, but then remembers Kaede once telling her that she had a little sister.

Mahiro suddenly puts two and two together and realizes that Momiji is actually a girl. Mahiro questions Momiji on this, and Momiji is a bit embarrassed that Mahiro thought she was a boy, asking if she really looks that much like one (adding that she gets that a lot). Kaede takes the baseball cap off Momiji's head and tells Momiji that she should just wear a skirt or something.

Mahiro collapses on the ground in relief remarking how she's saved. Kaede wonders what Mahiro said, while Momiji doesn't get it.

Later at home, Mihari makes a hotpot with the ingredients. While she and Mahiro are eating, she remarks that she knew about Momiji and realizes that she's in middle school now. She mentions how Momiji was always kind and resourceful, which Mahiro agrees with. Mahiro mentions how she was nearly tempted down a dark path with Momiji, leading a shocked Mihari to point out that Momiji is in middle school. Mahiro clarifies that that's not what she meant, and points out that she is technically the same age as Momiji now.

Mahiro then realizes that since they are both girls that would make this yuri. Mahiro is shocked at this as her resolve has been shaken.

It is revealed that Momiji proved that she was Kaede's sister by showing that they have the same phone charm: a fried shrimp, which leaves Mahiro confused.

Characters

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

Trivia

 * Mihari references when Mahiro took care of her when she was sick in "Mahiro the Own-Home Security Guard".
 * Mahiro references when Kaede first mentioned that she had a younger sister in "Mahiro's Unexpected Encounter".