English wiki: https://en.wikipedia.org/wiki/…League_Division_1_Men%27s
The important players of all teams in my opinion (only gives foreigners' nationalities):
Panasonic Panthers: Michal Kubiak (POL, OH), Hideomi Fukatsu (S), Issei Ohtake (OP), Tatsuya Fukuzawa (OH), Akihiro Yamauchi (MB), Takeshi Nagano (L), Kunihiro Shimizu (OP, injured)
Toyoda Gosei Trefuerza: Koichiro Koga (L), Taichiro Koga (L), Igor Omrcen (CRO, OP), Takuya Takamatsu (OH)
Toray Arrows: Antoine Rouzier (FRA, OP), Haku Ri (MB), Kentaro Takahashi (MB/OP), Naonobu Fujii (S), Satoshi Ide (L), Yamato Fushimi (MB), Yuta Yoneyama (OH)
JT Thunders: Thomas Edgar (AUS, OP), Liu Libin (CHN, OH), Taishi Onodera (MB)
Suntory Sunbirds: Dmitry Musersky (RUS, OP/MB), Yoshifumi Suzuki (MB), Takeshi Ogawa (OP, half Southwest African)
JTEKT Stings: Yuji Nishida (OP), Valentine Bratoev (BUL, OH), Hiroaki Asano (OH)
Osaka Blazers Sakai: Nikola Gjorgiev (MKD, OH/OP), Yoshihiko Matsumoto (MB), Masahiro Sekita (S), Takashi Dekita (MB/OP), Naoya Takano (OH), Shunsuke Chijiki (OH)
FC Tokyo: Jason DeRocco (CAN, OH/OP)
Oita Miyoshi Weisse Adler: None
VC Nagano Trident: None