[2][3] His older brother Daigo Watanabe was also a professional soccer player with Kyoto Sanga FC, Omiya Ardija, Busan IPark and Kamatamare Sanuki.

[5] He kept up his scoring exploits throughout the 2009 season and finished with 13 league goals which broke the previous record for a rookie player set by Shoji Jo in 1994.

2013 was a highlight for him as he bagged 17 goals in 33 league games to help the men in blue and red finish in eighth place in the final standings.

[6] He made a scoring debut for the men in blue and black with a 27th-minute strike to break the deadlock in a league match away to Vegalta Sendai.

[8] Watanabe made his full, senior international debut for Japan on 6 January 2010 in a 2011 AFC Asian Cup qualifier against Yemen.