|Inashiro High School - No. 3|
|Bats: Right||Throws: Right|
|Age||16 (debut) |
|Date of birth||22 August|
|Place of birth||Tokyo|
|Height||180 cm (5' 10.5")|
|Weight||85 kg (187 lbs)|
|Education||2nd Year High School (debut)|
|Anime||S1 - Episode 45|
|Voice Actor||Shō Kawaguchi|
Yamaoka Riku is a student of Inashiro Industrial and fourth batter of Inashiro's baseball team.
Yamaoka is a quiet person who hardly says anything. He is calm during games and enjoys drinking large amounts of water.
West Tokyo TournamentEdit
Yamaoka is first seen drinking a bottle of water while his teammates chat about Narumiya before Inashiro's semifinals match against Sakurazawa High begin. At game time, Yamaoka contributes runs for his team in the fourth inning. The combined efforts of the team, eventually led to Inashiro's utter victory.
In Inashiro's match against Seidou High School, he gets struck out with Furuya's fastball early in the match. But after a pitcher change, Furuya is replaced by Tanba, Yamaoka scores a solo-homerun right off the bat, affecting Tanba's pitching for a short while.
In the latter innings, he hits Sawamura's crossfire and gets on base but gets out when attempting for second with a risky play from Sawamura.
In the bottom of the ninth, when Inashiro scores their fifth run of the game, Yamaoka celebrates with his teammates.
In the third round of the Spring Tournament, Inashiro Industrial face-off against Yakushi High. At the top of the sixth, Yamaoka hits a RBI giving his team a second run. And in the eighth, hits another RBI for Inashiro's third run.
Relationship with other CharactersEdit
Yamaoka entered Inashiro Industrial after being invited by Narumiya. He thinks highly of Mei's skills and trusts him greatly. Like the rest of his teammates, he tolerates Mei's cheeky character.
Batting:Yamaoka is a power hitter and is capable of hitting home-runs. He was Inashiro's 6th hole batter, and currently bats 4th, after the third years retired (Harada's generation).
- He likes Records of Three Kingdoms by Yokoyama Mitsuteru, Sangokushi V (KOEI) 
- Has respect for: Lu Xun of Three Kingdoms 
- He played for Takahira Senior League together with Yabe Kouji. 
- Yamaoka (山岡) - Mountain Hill
- Riku (陸) - Land
|Narumiya Mei • Shirakawa Katsuyuki • Kamiya Carlos Toshiki • Yamaoka Riku • Fukui Kento • Yabe Kouji|
|Akamatsu Shinji • Yoshizawa Akimitsu • Mitsuichi Youji • Shima Ryouhei
|Former players||Harada Masatoshi • Yoshizawa Hideaki • Hirai Tsubasa