1. Jaejoong of JYJ
2. Changmin of TVXQ
3. Yonghwa of CNBLUE
4. Taemin of SHINee
5. V of BTS
6. Taecyeon of 2PM
7. Chanyeol of EXO
8. Heechul of Super Junior
9. T.O.P of BIG BANG
10. L of INFINITE
TWICE's J-trinity is somethin new, I've only heard of some Japanese members in UTTER nugu's like Cross Gene (??? pfft just a guess) and other flop company boy groups. And...Seventeen's Hoshi.
Hoshi is Korean hun.
Also Kangnam of MIB is half-Japanese, if that counts