They decided to make his the last route as sort of a bookends situation. His route will apparently need triggers from the other routes
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I think it's smarter too, because everyone who's here, wants a Torahiko route, since his route never existed in the original.
Which means once they finish his route, it's probably the end of the project, the interest it gone. They can't monetize with Morenatsu but no one wants to work on a project that people lost interest. And that interest is lost as soon as Torahiko's route is done.