Those virtues are the premise, a mix of harem, rom-com with suspenseful mind games, and how its development is promising at first which is tied to the MC (Maru) development through the story which it happens along with other girls of the harem.
However, is the execution where it greatly fails.
The story tries to blend rom-com with mind games (which include alliances, plot twists, and info dumps) among the members of the harem. Turning each arc into some sort of Battle Royale where the objective is to make Maru fall for one of the girls and to achieve that each of the girls will use any means possible they have on their hands and all of that happens in parallel to the story's progression which is about Maru's revenge and the aftermath of it and at first sound cool. But once the development start none of those aspects blended well.
The mind games are rushed, often predictable, and other times do not make sense in their development...or they are too high IQ for my stupid brain. Besides, on top of that, some of their resolutions are lackluster compared to the long speeches and infodump the anime throw about the plans.
Following this, the story development, which is Maru's revenge on Kachi and its aftermath, is decent but not good enough to compensate for the badly executed suspense elements and that's because this part of the plot also relies on suspense and plot twists to move forward the story...which are also rushed and badly executed but this time from the supporting cast side beside the members of the harem. Making Maru the only member of the main cast to not act as a 4d chess player and more like their charming pawn.
The comedy goes unnoticed most of the time outside the usual harem shenanigans (situational misunderstandings, jealousy between the girl and the "Kyaaa! Hentai!" types of jokes but without overreactions) but once they landed they were not strong enough to make me laugh besides just drawing me a soft smile in my face.
The romance section is a bit more developed than both previous points despite starting vanilla and plain but it starts gaining steam as the story goes on and even reaches interesting peaks during later episodes and actually reaches a remarkable point in the final arc. But, as a tradition with LN or Manga adaptations, all of this is thrown away at the last minute but at least the status quo and the situation of Maru are different from the start of the story but don't wash away the bitter sense the season finale left.
Furthermore, while the cast is colorful, grows through the story, has enough screen time to know about them, and are active in the story they are not remarkable and while they are not plain, they are neither interesting on their own. I would have overlooked that if the suspense part was implemented better since is when the harem (Kuro, Kachi, and Momo) show their selfish side to get Maru's love where they shine.
Finally, in the production, Doga Kobo dropped the ball in this but not hard enough to be unwatchable if you are not picky. Actually, the dance sequences are not CGI.
Overall, Osamake is more aimed at anime rom-com connoisseurs who just want to watch something to kill time. Because while it tried to be something interesting and captivating it failed on it and only the rom-com elements were the ones that kept it afloat.
