Oniichan ha Oshimai Vol 10 - That was a nice touch with Matsuri. Momiji!

Volume 10 of Oniichan wa Oshimai! (Onimai: I'm Now Your Sister!) continues mostly along the same line of development as previous volumes, with a few nice surprises along the way, particularly regarding the relationships developing between the cast members. The yuri undertones are still there and growing too!

Time is passing in the Onimai world, and they are now third-year middle school students, which means graduation is approaching. New uniforms, new looks, but mostly the same characters. The real change I saw was in the university students, especially Momiji's sister, Kaede.

Now third year, time sure passes. I wonder if it'll be over with this third year or they move to high school.

Gal mode Mahiro is quite powerful, but I like Momiji too in this mode, much more 'girl'.

It has been a while since I read a volume, but she has completely removed all the gal influence from her style, to the point that I was wondering if she was even the same person while reading. I mean, I was not a huge fan of her extreme gal style, but now it is the complete opposite, and I am kind of conflicted.

Among the stories presented, I was particularly fond of the one where Mahiro cooks something (hot pot) for Mihari's birthday. It was nothing major, just some cozy time between the siblings, with Mihari reflecting on when she was a little kid and the bond they shared.

Don't do it Mahiro, we can still talk about it. I don't know anything, I'm innocent, I swear!

The realization you got Asahi sleeping next to you after waking up must be scary for various reasons.

It was a nice moment, made even more tender by Mahiro and Mihari's mother, Matsuri, returning home explicitly to spend time with Mihari on her birthday. It is a detail that many series skip, often relying on parents being "always working" or "dead" to justify their absence.

Oh, and we got a cute cat omake, where Mahiro and the other girls take a potion that makes them grow cat ears and tails. It was nothing serious, but it was fun to see them give in to the temptations of that form, such as being attracted to silver vine.

Momiji continues her courting of Mahiro, I wonder if she'll be happy or not once she understand Mahiro is a male.

Skinship between Mihari and Mahiro is one of the best part of the series for me. Love their dynamics.

I am not sure when to expect a new volume, though; this one was released in July 2025, which is nearly a year ago now. The series doesn't update often, usually taking around 10 months per volume, meaning a new one should arrive soon, but I haven't seen anything pop up on BookWalker yet.