For 4,500¥ (about $40), you can spend the night inside a bookshelf.
The beds are strictly for people who expect to pass out while reading. The hostel’s site warns:
The perfect setting for a good night’s sleep is something you will not find here.There are no comfortable mattresses, fluffy pillows nor lightweight and warm down duvets.
The hostel opened in November last year with its smallest beds (80cm × 205cm) going for 3,500¥.