Found a really good Japanese site with free sound effects including voices, the site is entirely in Japanese but does include English URLs and sound previews so you can get an idea of what to expect before you download the sound. As for terms, since the site and Twitter are in Japanese someone fluent may have to confirm, but according to Google Translate their Twitter says, "It is OK for personal commercial use, and you can feel free to use it without the need for usage reports and credit notation", so I guess it would be CC0. The front page seems to have one restriction, "cannot be used by corporations" (again Google Translate, needs to be confirmed), but I guess individual devs or smaller teams can use these sounds without restrictions.
Viewing post in The Big List of Free Sounds
So apparently they've added a FAQ that while still entirely in Japanese seems to clarify that permission and credit is not necessary and you can monetize anything you make with their sounds. In fact, if you use them in Adult works, you are free to do so under the condition that you NOT credit them or link back to them in that case.