Hi, I have just complete my Entrance exam, anxious whether I could pass it or not.
I don`t know that exactly you want to know because your data is too little. However, as far as I know, if you intend to learn in Japanese, then you may have to take Entrance exam. The contain of entrance exam is different by which University and which Department, which program you wish to study. Normally, Entrance exam have 2 round: Round 1 - Writting (test your English skills,ツ knowdlege about field you intend to study). If you pass round 1, then you go to Round 2 - Interview about your Research Plan.
ツ ツ About how hard the Entrance exam is, I think, it depend on your program, your University. If you choose famous University like Todai and popular program, it will be touch. However, if there is a unknow private University, it may be too easy. Even in my University, the Entrance exam of some Graduate school is easy, some was diffcult (just my own opinion).
What do you mean when you said management? Is it MBA program? Since my major is Economic, I can say that with MBA program you may have any background (at least you have special skills), it only a little hard with peopel major in language. A manager can be in every company from production to service, so there is no need to care about background.
Anyway, all of my experience is about Master program in Japanese. I heard that some master program in English does'nt need to take Entrance exam (cause they check your ability before grant scholarship) or just need to take Interview. Don't know whether it true?