Mahiro Attends a Party

Mahiro Attends a Party (まひろとパーティーナイト, Mahiro To Pātī Naito) is Chapter 15 of Onimai: I'm Now Your Sister. It was originally published on Pixiv on April 28, 2018.

Summary
Mahiro and Mihari attend a Halloween party at Kaede and Momiji's house.

Plot
Mihari comes at Mahiro groaning, her head wrapped in two bandages. Mahiro freaks out and asks her what this is. Mihari snaps out of and tells Mahiro to calms down, telling her that it's Halloween; she was dressed up as and acting like a zombie. Mahiro yells at her not to waste her time with some stupid holiday, noting that Mihari knows how much Mahiro hates being festive. Mihari then points out that she was about to invite Mahiro to Kaede's house for a party, and asks her if she's staying home then. Mahiro agrees, saying that she can have fun once in awhile, much to Mihari's apporval.

Mihari has fun by giving Mahiro a cat suit with a hood that has kitty ears and full paws on the hands, making Mahiro look like a little kid who is dressing up.

When the two get to Kaede's house, Mahiro tries to scare Kaede with it by saying "trick or treat". Kaede at first appears frightened, but then hugs Mahiro telling her how cute she is. While doing so, she presses Mahiro's face into her bust, muffling Mahiro's words but also causing her to think to herself that Halloween is the best.

Kaede notes that Mahiro is really into Halloween, and Mahiro becomes surprised that she's the only one in costume. She remarks that she thought that this was a costume party and starts crying, realizing that Mihari tricked her. As Mahiro collapses onto the floor in embarrassment, Mihari tells her not to worry as she looks great. Kaede, thinking that Mihari is also in costume, asks her what she is dressing as. Mihari says that they are her normal clothes, and Kaede says that she figured that, Mahiro is overjoyed for being able to get back at Mihari for tricking her like that. Kaede tells Mihari that she shouldn't tease Mahiro so much, and Mihari ultimately agrees to that.

Kaede and Mihari put on aprons and say that they are going to get dinner ready, and Kaede suggests to Momiji that she and Mahiro go and play; Momiji agrees. Mahiro takes off the hood saying that she really wants to change out of the costume, and Momiji offers to lend her something.

In Momiji's room, Mahiro removes the costume and becomes amazed at being able to see what a real schoolgirl's room looks like. Momiji says that she doesn't have anything cute, but Mahiro is fine with that. Mahiro is a bit disappointed about the whole costume thing, saying that she really wanted to see Kaede in something sexy. Momiji ultimately admits that Kaede does have the figure for it, and compares it to herself who is still flat as a board. Mahiro tells Momiji that she is still growing, and that she'll be just like Kaede someday. Momiji remarks that she thinks that Keade stole all the good genes, and calls Mahiro lucky saying that Mahiro is already filling out. Mahiro is suprised by that statement, and realizes that now that she thinks about she maybe has developed a little lately. Mahiro starts to think how Mihari ins't exactly below average, and starts to realize that there may still be a chance for her to develop, smiling at the thought. Mahiro then snaps out of it and wonders why she just imagined that, the reaction of which surprises Momiji.

Mahiro is determined not to let herself get away and declares that she is guy; a porn-loving, red-blooded guy. She curls up in a ball, and ends up realizing that the clothes Momiji wore smell like a girl. Momiji tells Mahiro not to sniff them.

Mahiro, in a slight trance, gets up and says some people say that a woman's bust grows bigger if you massage it. Momiji is left surprised, and the two suddenly remember the embarrassing groping incident that happened the last time they hung out. Kaede opens the door and tells the two that dinner is ready. Mahiro and Momiji say okay, and are secretly relieved that they were interrupted before it got any weirder.

The dinner is pumpkin themed, much to Momiji's enjoyment. Mahiro groans, saying the she doesn't like squash, only for Kaede to quickly feed it to her telling her to only say that after she tries it. Mahiro tries it and immediately beams at how good it is. She thanks Kaede calling her the best, only for Mihari to point out that she helped make the food too.

As they continue eating, Mihari starts to laugh and Kaede asks her what's up. Mihari says that she was just thinking how it's been awhile since she and Mahiro had dinner with other people. Kaede realizes it as well, mentioning how Mahiro and Mihari's parents are overseas. She asks if their brother comes home sometimes, causing Mahiro to panic.

Mihari is surprised by that statement and asks Kaede what she means. Kaede says that she heard that her brother was at a far-away college or something. Mihari understands what is happening, and claims that her brother is busy with school. Kaede mentions that she never got to meet her brother and can't even remember his name, and recalls that Mihari used to talk about him all the time in middle school. Mahiro is surprised by this, and Mihari starts to panic.

Mihari changes the subject by suggesting that they all take a trip somewhere. Kaede is surprised at the statement that came out of nowhere, but admits that the weather has been getting colder lately. Mihari suggests going skiing, which Mahiro immediately calls "a big n-o". Mahiro instead suggests going to a fancy beach resort where it's warm and then take it easy in the air conditioning. Momiji remarks how going somewhere hot to be cold is true decadence. Kaede remarks that the travel costs might be high though, and suggests that they stay at a nearby hot spring instead. Mahiro says that a hot spring sound great, and Mihari lets out a sigh of relief.

Mahiro and Mihari leave, thanking Kaede and Momiji for having them. Kaede and Momiji tell them to come and see them again soon. Mahiro remarks that she is stuffed and that she never knew that parties could be this fun. Mihari points out that the reason for that is because Mahiro never tries anything new on her own.

Mahiro then remember what Kaede said about Mihari talking about her so much in middle school, much to Mihari's shock. Mahiro says that she doesn't know about all the terrible things that she must've told Kaede about her, but lets it go as it's all in the past. Mihari remains silent at this, then quietly says that she wasn't badmouthing Mahiro. Mahiro asks her if she said something, which Mihari immediately denies.

It is then shown that Momiji tried on Mahiro's forgotten costume, being amazed by it while Kaede watches on from the doorway and smiles.

Characters

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

Trivia

 * Mahiro and Momiji remember the embarrassing groping incident that happened between them in "Mahiro's Wholesome Playdate".
 * First mention of Mahiro and Mihari's parents, with Kaede mentioning that they currently overseas.