A fairly minor one: why does Miss Sakie not have a car, or at least a bicycle, given how far from others she has to live?
It's likely cheaper to take the train than keep, fill with gas, and maintain a vehicle. It's also likely faster considering Japan's train system.
Yes, that's true. But why does she not have at least a bike to get herself to and from the station?
More pressingly, why does she take public transportation at all, given the fact that she's a succubus seriously afraid of too-close proximity to others? With how early she has to get up and late she has to stay for the sake of taking the train at the least crowded times, you'd think a car would be worth it just for the stress relief. If she drove a car it'd just be her in there, she'd be able to arrive and leave places at times convenient to her, and she'd likely be able to get a lot more sleep.
Again, the cost is probably the key factor. That plus her proximity wouldn't be impeded by the confines of the car. If travelling during rush hour, she could possibly cause a major accident or two. The manga also begins to address this issue by showing the school has a night room she's able to use a few times a week to avoid travelling back and forth.
It's mentioned that most succubi, and especially those as potent as Sakie, receive a government pension so they minimize all contact with society. Sakie wants to earn her own living and does so as a teacher. She takes public transportation because that's what she can afford on her salary (she just became a teacher). Though the government would like Sakie to just take a free paycheck and do what you inquire, her social worker admires her resolve and does what he can for Sakie to live a normal working civilian life.
