I don't know much about J-POP music since I just moved back here after 9 years living in US but I can give you some artist's name...
- EXILE (R&B, guys group)
- Chemistry (R&B duo)
- Mr. Children (rock band)
- B'z (rock duo)
- Hikaru Utada (R&B, Pop, female)
- Ayumi Hamazaki (Pop, female)
- Crystal Kay (R&B, Pop, female)
- Kumi Kohda (R&B, Pop, female)
These are just a few artist's that I know that are popular in Japan. There are a lot of new artist that I've never heard of.....sorry I couldn't deliver any latest info.
Hope you can find one for your sister....what kind of music does she like?
Mickey