Morita therapy - does it have a western counterpart?
Reminds me a bit of existential therapy and humanistic psychology in general. Unconditional positive regard and motivational interviewing both insist on approaching undesirable feelings from the client's perspective without imposing fixes or changes on the person through pressure or blunt confrontationality. Existential theory even presumes major, inevitable negativity in life experience for which no individual could be blamed. There are plenty of terrible realities for every individual to face and accept in the process of adjustment and maturation. The individual must do this freely, idiosyncratically, and earnestly for oneself, or so the theory goes. Focus is not on eliminating negativity but on finding meaning amidst it. I hope these Wikipedia pages give you plenty to read for starters, but I can try to find more if you like.