It's not really Shimbori, it's KT. Character design and approach is not always a director problem. You can have a new director and still follow the same direction.
They also have their own boss. It's KT executives and their marketing team.
Yeah KT controls the background of it all along with their budget. It's literally a business unfortunately. It's why the game is ultra niche on top that the feedback is a lot more better received in Japan than the west and why we end up with bad content. It goes without saying "What Japan likes is what we are forced to get".
When you make a game, there is a budget amount given. Shimbori and his team uses that budget, but sometimes you can get a lower budget than intended because of profitable returns. KT expects the game to sell like millions even with a lower budget because in their minds is basically "it's just a bunch of horny teens, it'll sell trust me." as well as catering to another demographic.
They also have their own boss. It's KT executives and their marketing team.