1.Train scene happens if you molest Hadzuki enough times on the train without raising suspicion to max. It leads to another scene in the office at night, but that also gets you a bad ending.
2.Office scene is a bit tricky, because she is asleep and you think you need to drug her (like the Kouhai). Instead, as the person above stated, do not go home with her and return to meeting room post-work time.
3. Sigh.... I get it, it's hot and it also leads to a preg scene. However, you want to play the moron to get the two versions of the bondage scene there. After you get any of the two main endings (Hadzuki gives birth your children) you get an invitation from the red brick building to participate in auctions of kidnapped girls, events during which you may recover the girl you sold to the clowns (chance of her appearing may vary). You buy them, you train them (shitty training with little erotic content) and then you auction them to get your money back and more. After you auction 3 or 4 girls, the patrons of the house invite you to auction Hadzuki. Because you are now a moron, you accept the invitation to a game you have nothing to gain from... and of course, the house edged the bets so you lose no matter what. The scene you want has Hadzuki becoming the property of either some rich guy or a breeding factory.... Congratulations, you get a preg/bondage/mind break set of scenes at the cost of losing your girl.
