There seem to be a lot of different long term accommodations to choose from in Japan these days.
If you are looking for something unique and different and wishing to make friends or socialize with other tenants at the same time, a new style of apartment, “Social Apartment” may be the answer.
The rooms are rather small with private bath/toilet and a compact kitchen but they look modern and sophisticated. The rent may not be super cheap but reasonable and conveniently located. Some are in the mid-centre, some attached with a laundry and a fashionable cafe, but all has a community lounge to socialize with others.
If you need to stay in Japan more than a year, this new style of Social Apartment could be best suited for your needs.
Official website (English): https://www.social-apartment.com/