[1] He learned how to play shogi from his father,[2] and was a well-known strong amateur player as a teenager, performing well in a number of national tournaments.
[3][4] In 2005, he won the 34th Asahi Amateur Meijin Tournament [ja], becoming the youngest person to do so up until that time at the age of 19 years and 3 months.
Wanatabe's victory also meant he qualified to participate in the 24th Asahi Open [ja] where he continued his good play, winning three straight games against shogi professionals before finally being eliminated from the tournament.
[4][6] The following season, Watanabe earned a second promotion point after finishing the 43rd 3-dan League (April 2008 – September 2008) in third place, once again with a record of 13 wins and 5 losses.
[2][3][4][5][7] This gave him to option to obtain full professional status and corresponding rank of 4-dan as a "Free Class" player.