Oniichan ha Oshimai Vol 8,9 - Mashiro's mother Matsuri is here?!

March 15, 2026 · 8:01 PM

Volumes 8 and 9 of Oniichan wa Oshimai! (Onimai: I'm Now Your Sister!) actually surprised me by introducing a brand-new character out of the blue. For most of the series, we have seen Mahiro and Mihari living alone in their house, and no one ever questioned where their parents were.

It turns out their mother, Matsuri Oyama, works abroad and only returns home rarely. This visit is particularly complicated because of Mahiro's new appearance. Mahiro panics and decides to hide on the rooftop to avoid being seen, but this inevitably backfires. Mahiro is discovered, but nothing dramatic happens. It turns out Mihari had already notified their mother about the situation, so she knew all about it.

The combination of Mahiro and Mihari is still the most common in the story. They're siblings after all.

Where is Asahi? Usually it's all four together, but here we only have Mahiro, Miyo and Momiji.

Matsuri is a cheerful mother, the kind who loves hugging her children and taking photos with them. On top of that, she looks extremely young, to the point that she is easily mistaken for an older sister. We even see a picture of all three of them—Mahiro, Mihari, and Matsuri—in school uniforms, and Matsuri does not look out of place at all.

There were plenty of other interesting scenes as well. The first that comes to mind is Mahiro's outing to get an item from a gacha machine. While she fails to obtain the item, she encounters Kaede and two of her friends, who are all cute "gals."

Seems like Mahiro's mother Matsuri loves taking photos with her kids. Seems like a fine mother and I can see from where Mahiro took her looks...

Mihari sometimes look a lot younger than she is in some of the art. I like the style though.

They take her along to have fun together, which results in Mahiro completely changing her style to look more like a gal. I quite liked her in this new form. Later in the volume, we even see Momiji adopt the same style because she was jealous that Kaede did not invite her. Usually, Momiji does not like going out, but when it involves Mahiro, things are different.

Another pair of extremely good scenes I want to mention are both related to Miyo. The first involves her finding an unexpected friend in Aoi Tachikawa, the class representative. Initially, there is a funny misunderstanding between the two because Miyo is deeply into yuri manga while Aoi is heavily into yaoi.

She got discovered straight immediately, never underestimate the power of mothers!

Just look how cute they are together. Matsuri is identical to Mahiro right now in terms of looks, genetics are strong.

The two were talking about the same thing—the interactions between their classmates—yet referring to completely different targets. The issue was that they spoke in such a vague manner that each thought the other was talking about the same thing. Eventually, they open up and exchange manga. While they both maintain their original preferences, they end up enjoying the other's content as well.

The second scene involves Miyo visiting Mahiro's house daily to play a yuri game together, as she has become engrossed in the story. They spend many hours together without revealing the real reason for their meetings, leading people to believe they have actually become a couple.

The gal power here is overwhelming, Looks like I love them in this form too!

More cute family scenes with Matsuri, Mahiro and Mihari, really like these. Shame she won't be around for more.

The tension is defused when Mihari bursts into the room, expecting to find something obscene happening between the two. Instead, she finds Miyo completely hypnotized by the yuri game, to the point that she starts calling Mihari "oneesama" while trying to hug and kiss her.

Overall, it was an enjoyable experience that reignited my love for this cute type of manga. I need to start searching for more to read soon, as I am getting close to finishing the series I am currently following. Expect me to start some new titles shortly.

Yuri blooming between Miyo and Mihari? Where should I sign to get more of this?!

Here Matsuri looks a lot more 'mother' than 'older sister'. I guess it depends a lot on the expressions she does.

I had a sneak peek at the next volume, and it seems we are going to see more of the "gal" forms for Mahiro and Momiji. I am interested to see what situation they will get into this time. I will likely wait until another volume is available before making another post.