Cheap bike
Caroline needs a bike but doesn't want to spend a lot. "I heard I can buy, very cheaply, bikes that have been left at inconvenient places, such as train stations, towed away and not retrieved by their owners after a year. Can you give me more details about where such depots might be?"
She remembers years ago when living in Segenjaya that she had to go somewhere on the Den-entoshi Line to get a bike back, but can't remember exactly where.
Your best bet, Caroline, is to go through your local city office. It is usually their staff that are responsible for collecting bikes left in places where parking is prohibited. Your local "koban" (police box) will also know where the nearest depot is.