Guidance on preparing to make a switch to MO/BO at Japan?

I'm a current IBM Business associate consultant. My first job was working for a French Bank at the back office for FXMM settlements. One of my bucketlist is to work in Japan, so I am planning a switch in 3 to 4 years time. The thing is... I went on to make a simple google search and everything from consulting to IBD to compliance (you get the idea) requires strong Japanese level.

Now I'm trying to learn Japanese but is not easy. Which brings me currently thinking which banking role should I get if I want to work in Japan with an alright level of Japanese (I think I should be able to reach JPLT N3 in 3 - 4 years time)? I will leave my consulting role. But should I join back for a back office settlement role at FXMM? for equities? for reconciliation? Or join a middle office operation role at an asset management firm? I'm not a technical person so I won't be able to work on market risk nor I'm remotely interested in front office.