Say what you want about Studio Ryokucha, but their weird plotge/charage hybrids are some of my quirkier favorites. To be specific, Minamijuujisei Renka is my favorite game by this company, at least partially because of how deftly they sidestepped the worst of the 'high school' tropes while keeping the advantages of familiarity.
Minamijuujisei Renka is based on a fictional island still ruled by a post-colonial Caucasian aristocracy that long-since lost its connection with its long-dead original nation (I'm guessing Prussia is the model for the fictional dead nation, based on certain aspects of the setting). It has achieved a high level of technological and societal development despite being handicapped by a small land area, a relatively small population (just around a million), and the gap between the aboriginal population and the white aristocracy. The game's true/main heroine, Kanori, is the half-white, half-Japanese princess and currently the sole heir to the nation, a fact that has the more conservative elements grumbling about mongrels and other predictable purist BS.
The protagonist of this story, Tobe Ryousuke, meets Kanori by chance on his first day in the nation, when he gets lost and encounters her while she is fleeing from men in black. This leads to a predictably amusing set of small chase scenes, and it also solidifies Kanori and Ryousuke's relationship (her in love with him, him thinking of her as a friend) before he ever realizes who she is.
Ryousuke came to the nation involved along with his twin sisters, little genius girls who, when he collapsed from exhaustion trying to take care of them, took a job in the Dukedom in order to allow him to go to school and be a normal kid, essentially. Rina and Rena, the twin sisters, are both children (literally), and their cuteness of both manner and feature serves as a constant throughout the game, as they often appear at important moments to move the story forward. There are hints that if 'nii-chan' didn't have the good taste to get hitched before they were grown, there would have been some incest there, but, unfortunately for the lolicons out there *laughs at them* and fortunately for our peace of mind, they aren't heroines.
Anyway, this game is designed with a chapter system, where incidents occur and get resolved, bringing the protagonist closer with the heroines throughout the common route. This system often falls flat in games that use it, because it can get repetitive, but the creativity with which the writers set up the story makes that a non-issue in this game. Like a lot of games from the middle of the decade that just ended, most of the heroines are deredere almost from the beginning (the exception being Elize, though it can be argued she is just another tsundere along with Miyako).
Unlike many charage hybrids, this game doesn't kill the story in the heroine paths or only have the story in the heroine paths... rather, the story flows in different directions based on which heroine you pick, and it feels natural at the time, which is what is important. There are exciting moments in each path, without it flowing over into excessive seriousness (most of the story is interwoven with amusing or cute elements).
Though the story is good in this game, perhaps the place where this game shines the most is in character development. By the time the common route ends (it is fairly long), you have a solid idea of what all the heroines are like under the skin, and you have almost definitely gotten attached to one or more of them. Tbh, each time I play this game, I always waver between routes before making my choice, simply because I like all the heroines to one degree or another.
This game's weakness, from an objective standpoint, is the very length that allows for such extensive character development. Many simply won't have the stamina to finish even one path in a single run, due to the length of the common route. To give you an idea of its length, it is roughly the same as the common route of Clannad.
I occasionally go back to this game for one reason... it is so reliably enjoyable that just finishing a single route can temporarily restore my faith in the possibilities of charage.