Break up the soap in to small pieces. The smaller the chunks, the faster they will dissolve.
Heat the water, shampoo and soap in a sauce pan. Stir until all the chunks dissolve.
Take off the heat, pour in to a jug and add the shots of sake. You can also add essential oils now, if you'd like more of a scent.
Use a funnel to pour the bath soak in to a nice bottle and decorate. Enjoy a few generous drops in a hot steamy bath.