Small (non-kinky) store selling all types of ropes (for construction, wrapping etc). They carry jute, linen & coconut ropes, that can be purchased by the length (or by spools of ~120m). Famous for being where many established Tokyo riggers get their untreated rope.
Although in no way familiar with the scene, the adorable little old lady who runs the shop is more than happy to help with advice on quality, etc (she does not speak any English).
They also occasionally sell dyed rope, although quality varies.