https://web-ace.jp/ Although only "Young ace up" is totally free for now
https://comic.jp/comic For some of them, only 1-3 volumes are free
https://newtoki95.com/
For manhwa: https://tkor.tube/%EB%AC%B4%EB%A3%8C%EC%9B%B9%ED%88%B0 reply
here are some LEGAL sites/apps where you can read JP manga. Some of them follow a coin system (that you can earn by logging in or ads), some have ads every few chapters, some don't have any but after a certain time period (usually a couple of months) you can't read older chapters. some apps have promotions where a whole series, or chapters hosted i...... reply
Manhuas(these sites also sometimes have chinese raws of korean manhwas):
https://www.kuaikanmanhua.com/
https://ac.qq.com/
Manhwas:
https://tkor.tube/%EB%AC%B4%EB%A3%8C%EC%9B%B9%ED%88%B0 reply
