“Moving“ to Japan for ~5 months

As my job offers a 6 month sabbatical I was thinking of taking it and using that time (which would boil down to about 5 months) to visit Japan and improve my language skills. I also know that getting an apartment can be quite difficult and maybe not even possible for that short of a timespan. Does anyone have any tips where I could look to find a place to stay. Should i really be looking for a flat or could I just stay in (preferably) one/two hotel(s)? Are there any alternatives?

In regards of jobs: As I will continue being paid by my now job I don‘t really have to and also don‘t really want to use a working visa and just enjoy my time off by traveling and relaxing.

Bonus question: How would this work in regards of a visa? Different websites said that a visa isn‘t necessary for up to 6 months, others state that you need a tourist visa which would only be valid for 90 days.

Also I‘m sorry if that question sounds dumb or was already answered. I just don‘t have any experience with this kind of situation.

by CryptographerThat168