Anyone figure out how to get the alternate routes yet?
So far I've gotten the canon route, the slutty route, and I guess the tomboy route?
Mature girly route: low manliness, possibly high Friendship with Villagers, pick a non-sex book
Bratty girly/sex slave route: go to the shop in the north west of the western map (the one run by Gummo's dad), and interact with the pink star. Skips book selection. This might only be if you are girly in the first evolution (note: very rape-y)
Depressive route: low Brightness of Personality, low Friendship with Villagers, non-sex book
the rest for completeness:
Canon route: moderate everything/failed to get anything else, pick a non sex book (probably easiest to get without trying)
Slutty route: pick the sex book
Tomboy route: high manliness (> 100 I think), high stats in general, pick non-sex book
note that most routes have a much less interactive final stage if you tell the protagonist kid/nanashi you love him right before the second evolution.
(corrected a bit from Chipp12's post)