For those of you interested and don't follow the scene closely, I'll give you a quick overview of who the current best in Japan are.
S+ Rei Chan
S Kusoru, Nemo.
Confirmed going to Final Round 16: Abegen VxDante
Rumors Rei Chan's lack of interest to go to USA and playing in a tournament has gone from 0% to "he may consider it" according to numerous Nico sources. Though it has been said that Kusoru isn't going to Final Round by players that know him, there are whispers claiming people at FR are making an effort to get him there. As Nemo's cockiness grows, so does his aspiration to play in USA. It was previously rumored that he's trying to get to Final Round. However that seems unlikely. The UMVC3/SF international representation for Japan and USA @ WGC may not be as appealing as advertised. RF and Fuudo participation still is questionable as well as USA players like Dieminion.
SF4 Players. Recently a lot of top SF4 players have picked up UMVC3. I suspect these will be the bulk of Japanese to represent Japan in UMVC3 for EVO. Here's some to keep your eye on---
Eita: Top but inconsistent Akuma. Plays a number of different teams in UMVC3. Kazunoko: #1 BP Yun in Japan. Currently plays Wolvie/Akuma/Vergil. Banbaban: Top Yun and Cammy player in Japan. Currently plays Wolvie/Doom/Vergil. Acqua: #1 BP Cammy in Japan. Currently plays Nova/Strange/Spencer Nemo: #1 BP Yang in Japan. Has been seen entering 5v5 AE tournaments. Top 3 UMVC3 player in Japan. Tokido: Top Akuma and potential top 5 UMVC3 player in Japan. RF: Top Sagat. Plays Taskmaster/Doom/Vergil.
There are other SF4 players playing the game such as Mago, Fuudo and recently Bonchan. Most of these SF4 players haven't been playing long but are rapidly improving and may pose the biggest threat come EVO outside of the top 3 if their current growth continues.