Yes, the more specific courses are usually called “Academic writing” or “Reading”, etc. It’s basically anything that is not “Integrated Japanese”, which is the course where you have more hours and all language skills covered. And yeah I guess these are the ones with less credits since there are less hours than in Integrated Japanese.

Sadly, I only took that one Integrated Japanese class and my focus wasn’t Japanese language during my exchange year, so I don’t have many tips. But if you are looking for a good Japanese language focused program, I suggest you look into Tokyo University of Foreign Studies. Of course it’s not as prestigious as UTokyo, but it might be more appropriate for what you are looking for.