Watch Sumo Do, Sumo Don't Season 1 in Australia

Ryota Moriyama, a senior at Kyoritsu University, receives a job offer at a top company but gets dumped by Saki Nishino. On top of that, he learns he will only be able to graduate on the condition that he joins the sumo club, which is on the verge of disbanding. Ryota goes to the club and finds Honoka Oba training there, who is suspicious of Ryota’s motivation for joining. Honoka begrudgingly agrees to let him join, but only if he beats her just once out of ten matches.

Honoka performs at an event to showcase school clubs to new students, leading to a sudden influx of male candidates. Arisa Tazawa, the club manager, is overjoyed and enters the club into the All Japan Qualifiers. However, the candidates run away after experiencing Honoka's strict training. Saki, the chief editor of the university's editorial club, shows up with Ren Noguchi for an interview. Ren becomes a fan of Honoka after seeing her perform and asks to be in charge of covering the sumo club, after which he finds out that Honoka was runner-up at a national tournament as a middle and high schooler. Despite the shortage of members, Kumada demands that they participate in a tournament. Ryota and the others recruit new members, allowing them to participate in the tournament.

Honoka runs into Tomio Aoki, an alumnus of the Kyoritsu sumo club whose book inspired Honoka to enroll in Kyoritsu University. However, the book is filled with lies, and the other alumni are still angry over it. Meanwhile, Kumada promises Ryota and the others a reward should they win just one team match. A student named Shun Kato visits the club under the pretense of doing an editorial cover story. Kato heads back to the dojo and runs into Aoki, causing a major commotion.

With four male members in the club now, Ryota and the team train hard. The day of the tournament finally arrives. Aside from Hokuto Gakuin, the other schools do not seem to be that strong. However, Ryota and the team are nervous for their first tournament. Kyoritsu's alumni gather to watch the matches with expectations. Ryota and the team are given a choice to quit. Ryota decides he has fulfilled the condition to graduate. Meanwhile, Honoka feels prepared for the female event taking place the next day and trains with the help of Kaito.

On the day of the women's tournament, Honoka once again meets Mayu Motohashi, the top wrestler for Meiritsukan University. Ryota distances himself from sumo but still wonders about Honoka's matches. He watches the video recordings of the matches sent by Shun, Ren, and Yuma, and is touched by Honoka's earnest attitude towards sumo. Ryota hurries to the tournament, making it in time for Honoka's semi-final match against Mayu. Although Ryota feels helpless in his own sumo skills, he realizes his love for sumo after speaking with Saki. Despite this, he cannot find an excuse to return to the dojo. Meanwhile, Honoka meets Sakurako Yoshino. She is surprised by her strong physique and invites her to join the sumo club.