Japanese tubs are typically used only for soaking in – in fact you generally wash before using one.
A Japanese style bathtub – they are great for soaking in. The one I liked was as wide as a tub but not as long, and deep enough to sit with water up to your neck – there was a low seat on one side. I don't know how available they are outside of Japan; I don't have one now, and sometimes toy with the idea of making one.
Patrick Murphy