Blu-ray Volume 2 Appendix Manga

The Blu-ray Volume 2 Appendix Manga is a special chapter of Onimai: I'm Now Your Sister!. It was released exclusively as a part of Volume 2 of the Blu-ray release of the anime series based on the manga which was released on June 21, 2023.

Summary
In this exclusive chapter which takes place in the anime's continuity, Mahiro and her friends have a party at Kaede's house after the recent hot spring trip to determine plans for the future.

Plot
At Kaede's house, everyone raises their classes for a toast and says cheers. Kaede dedicates the toast to their great hot spring trip that they have recently gotten back from. Kaede remarks that the hot springs were so nice, and Momiji adds that the sights were nice as well. All the girls share a laugh.

As Mahiro laughs, she notes that they are at a house party at Kaede and Momiji's house to celebrate their return from their trip. She notes that it almost feels like she's a normal girl. When Asahi grabs Mahiro to cheer, Mahiro notes that this might even make her a party animal.

Miyo notes that she would love to do something like this again and asks if the others would as well. Momiji remarks that they'd better go skiing then. Asahi says that they should do it, and suggests that they set sail tomorrow. Kaede tells Asahi to hold it for a sec and explains that there's no way they could make this ski season work for them. This leaves Asahi a bit disappointed, but Mihari tells her that there's no need to rush it as the four of them are still middle schoolers after all.

Mihari thus suggests that they simply start thinking over possible plans for the future and suggests that they could all go cherry blossom viewing once it's spring. Momiji is intrigued, while Asahi says that she'd love to munch some dango.

Mahiro is in the mood to have a barbecue, which leads Miyo to point out how much Mahiro enjoys meat.

Momiji says that when summer hits it'd be great to go to the ocean. Mihari notes that a pool would work just as well. Mahiro in that case suggests a night pool and invits Mihari to do it with her, imagining Mihari and Kaede in skimpy bikinis. Mihari nervously notes that that might be a bit too much. Asahi is confused and asks what a night pool is, but Mahiro declares that middle school is too early to open that particular door. Momiji guesses that it must be one of those trendy things.

Asahi notes in a scary tone that the pool of the night is terrifying, and begins to say something about the lingering grudge of the drowned schoolgirl. Before she can finish, Momiji puts her hands over her ears in terror and yells at Asahi to quit it. Asahi then suggests that they could throw a test of courage in there as well, which Momiji warns her not to.

Mahiro and Mihari watch as the others begin discussing plans for the fall. Momiji notes that it looks like there is still plenty of fun left to come, which Mahiro feels teased about. Mahiro then notes to herself though that leaving things the way they are right now can't be so bad, as the image of her new friends brings her much comfort.

Trivia
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 * According to Nekotofu, although the plot of the chapter is meant to be canon to the anime as evidenced by Asahi and Miyo celebrating coming from the hot spring trip, it's events can also be considered for the most part as canon to the manga as well. Thus, he designates the story as being "Chapter 18.75", taking place in between the events of "Mahiro's Perm" and "Mahiro the Streamer". He mentions that in the anime, the events of this chapter take place directly after the events of "Mahiro's Future as a Sister".
 * This chapter is meant to foreshadow a few events from the manga that have yet to be adapted into the anime:
 * The barbecue during golden week which occurs in "Mahiro and the Barbecue Secret".
 * The beach trip which occurs in "Mahiro's Beach Fun (Part 1)", "Mahiro's Beach Fun (Part 2)", and "Mahiro and the Squishy Thingie".