[sakuraiben]

Japanese software engineers are infamously known for working (usually forced) over time (i.e. forced to take out time card). Because software engineers work over time there is a urban legend that Japanese engineers retire at age 35. However I have to say these often apply only to large general contractors.

Corporate cultural is super rigid and is something you would definitely want to avoid, however I believe this is not always true for startups (especially in Tokyo).

As long as you belong in a English speaking team you should be fine.

Also just be careful of the contract type. Some companies who want to fire workers on the go will try to force some form of a temporary contract.