Mahiro and the Barbecue Secret

Mahiro and the Barbecue Secret (まひろとヒミツのBBQ, Mahiro To Himitsu No BBQ) is Chapter 44 of Onimai: I'm Now Your Sister!. It was originally published on Pixiv on September 26, 2020.

Summary
During Golden Week, Mahiro and her friends hold a beach barbecue party.

Plot
At the end of the school day, Mahiro jumps for joy as it's finally Golden Week. Momiji suggests that they should all do something together, which puts a damper on Mahiro's plans to do nothing. Asahi suggests that they go hiking, which Mahiro protests against, saying that that's just tiring. Someone else suggests they do a beachside barbecue instead, and this gets Mahiro excited. She yells to "bring on the meat", leaving Momiji amused.

Sometime later, everyone gathers on the beach and sets up for the barbecue. Kaede acts as the grill master and announces that it is time to get grilling. Asahi notes that she can't wait, but Kaede tells her to be patient as it takes time. Mahiro is impressed by Kaede's use of adult supervision.

Nayuta thanks Momiji and Miyo for inviting her. Momiji says that it'll be more fun with her here, and Miyo notes that it is so fresh seeing Nayuta out of her school uniform.

Kaede announces that everything is ready, and Mahiro gets amazed at how good the meat looks. Mahiro takes a bite, and is sent to heaven over how good it is. She notes that grilled meat is the best, and Asahi agrees with her. Kaede reminds them to eat all their veggies as well.

Kaede serves Nayuta, and tells Mihari to bring the rest of the meat. Nayuta bows to Mihari and excuses herself for eating ahead of her, leading Mihari to note how polite Nayuta is. Mihari asks Nayuta if she's the new friend that Mahiro mentioned, and Nayuta introduces herself, saying that she's pleased to meet Mihari. As Nayuta talks with Asahi, Mihari is sure that she's seen Nayuta somewhere before, but can't recall where.

Kaede gives Mihari her plate, and Mihari thanks her for it. Momiji offers Kaede a bite of her food, and Kaede opens her mouth eagerly for it. Mihari notes that Kaede and Momiji are so close. Mihari tells Mahiro to do it to her, and Mahiro reluctantly feeds Mihari a bite while telling her not to be greedy.

Mahiro finishes her meal and smiles, noting that she is stuffed, calling that mission complete. Mahiro says that it is now time for a nap, leading Kaede to laugh and Mihari to call Mahiro a lazy bones. Before Mahiro can rest, Asahi calls out to her. She asks Mahiro to come over to where she, Momiji, and Nayuta are. There are playing in the shallow water and say that it is nice and cool. Mahiro cringes at the idea of physical activity, but decides to go anyway, taking off her socks and shoes.

When Mahiro enjoys the feeling of the water on her feet, Asahi splashes some water at her, surprising her. Mahiro playfully says that Asahi has done it now and splashes her back, with the four girls laughing and having a splash battle. Kaede notes that it is a wonderful and perfect picture, thinking about how it must feel to be young. Mihari just laughs at the sight, happy that Mahiro is having fun with other people. She asks Miyo if she wants to play with them, but Miyo says that she just prefers to watch, aroused by all the girl-on-girl action that she sees.

As the splash battle continues, Mahiro splashes Nayuta to get her involved. Nayuta admits that she's never done something like this before, and splashes Mahiro in the face with an extremely large amount of water. Mahiro is so surprised by it that she falls backward into the water, completely soaking herself, much to all of their shock shock. Mahiro emerges in tears, all of her clothes soaked through, telling Nayuta to go easy on her.

Momiji helps Mahiro up and asks her if she's okay. Mahiro says that she if fine and just soaked, while Asahi tells Nayuta that that was a good one and places her hand on Nayuta's shoulder. Mihari gives Mahiro a towel and asks her what she was thinking, while Kaede gives Mahiro an extra shirt that she can change into. Nayuta feels bad that this happened all because of her.

Mahiro is left standing there, wearing only Mihari's jacket over the spare shirt that Kaede gave her. She tries to pull down the shirt in the front to cover up the fact that she is half-naked, while Kaede wonders if Mahiro's clothes will be dry by the time they leave. Mahiro cries slightly and asks Kaede if she can at least wear her underwear. Kaede refuses, saying that she'll catch cold as they're still drying.

Mahiro cringes, noting that this is the most self-conscious that she's ever been. Mihari just laughs slightly, noting that Mahiro is going commando. Nayuta apolgizes to Mahiro, but Mahiro tells her that it's fine and to not worry about it. Nayuta then grabs Mahiro's hand and tells her to come with her. Mahiro tells her not to go so fast, and she is still struggling to cover herself up.

Nayuta leads Mahiro to a secluded spot, and Mahiro asks her what they need to be there for. Nayuta tells Mahiro not to worry and says that she'll take responsibility for this. Nayuta holds up a pair of panties and tells Mahiro to take them, leading Mahiro to get happy at having a chnage of undies. Mahiro thanks Nayuta, telling her that she's so thoughtful. Nayuta notes that unfortunately they're only the bottoms, but Mahiro is still happy as it's still a load off her, and realizes that they're kind of warm as well when she puts them on.

Just then, a breeze lifts up Nayuta's skirt and Mahiro realizes that she has nothing on underneath it. Nayuta gets embarrassed, explaining that she thinks she's a little small to help her for the other. Mahiro realizes in shock that Nayuta gave Mahiro her panties to wear.

Asahi spots Nayuta, and announces it to Momiji and Miyo. Momiji says that they were looking all over for the two of them, and asks what they were doing. Nayuta covers up the front of her skirt, with she and Mahiro too embarrassed to say anything. Momiji demands to know what is going on, while Miyo gets aroused, as another misunderstanding begins.

When Mihari does laundry that week, she finds Nayuta's underwear. She asks Mahiro if they own a pair like this, as she doesn't remember buying striped panties, but Mahiro doesn't say anything.

Characters

 * Mahiro Oyama
 * Mihari Oyama
 * Kaede Hozuki
 * Momiji Hozuki
 * Asahi Ōka
 * Miyo Murosaki
 * Nayuta Tenkawa

Trivia

 * This is the last chapter for awhile where Mahiro and her friends wear their long-sleeved winter school uniforms. Starting with the next chapter "Mahiro and the Seasonal Attire" she and her friends begin wearing their spring uniforms.
 * As noted by the chapter, Golden Week is a string of official holiday celebrations in Japan in late April/early May.
 * This indicates that the events of this chapter take place in late April/early May.