The 70th Inter High School Mahjong Championships (第70回全国高等学校麻雀選手権大会) is the 70th edition of the All Japan High School Mahjong Tournament championships.
Teru Miyanaga led Shiraitodai High School of West Tokyo in defending its national title. Senriyama Girls' High School reached the final but ended the match with the lowest score, earning it fourth place in the championship. Led by Komaki Jindai's performance, Eisui Girls' High School reached in the finals, which earned them a top 4 seed in the next Interhigh. Himematsu High School lost their seed due to this.Koromo Amae of Ryuumonbuchi High School of Nagano was named the MVP of the tournament, and set the record for the most points earned. In her first match, she defeated two schools. In the quarterfinals, Ryuumonbuchi played against Rinkai Girls' High School of East Tokyo and Gappo Girls' High School. In the vice-captain match, Touka Ryuumonbuchi entered her "cold" state due to the power of the opposition. Rinkai's Megan Davin was afraid of her, and decided to attack Gappo Girls' instead of Ryuumonbuchi. In her match, Koromo managed to defeat all three opposing players. However, in the semifinals, Touka was defeated and Ryuumonbuchi knocked out, without facing Shiraitodai.