A third generation Japanese Brazilian, Kaisei made his debut in September 2006 and reached the top makuuchi division in May 2011.

Sugano used to train in many sumo clubs in São Paulo, where he ended up meeting the retired rikishi Wakaazuma Yoshinobu, who is also Brazilian.

He came through the September 2009 tournament undefeated (although he lost a playoff for the yūshō to Gagamaru) and in July 2010 became a sekitori by earning promotion to jūryō.

With the intai-zumo (retirement from sumo) of ōzeki Kaiō during the same tournament Kaisei become the heyagashira (the highest ranked wrestler) at Tomozuna stable.

In July 2012 he scored eleven wins, picking up his second Fighting Spirit Award and earning promotion to maegashira 1.

Kaisei made his san'yaku debut in the May 2016 tournament, having been promoted to komusubi on the back of an 11–4 record from the rank of maegashira 7.

He injured his knee training with Hakuhō shortly before the March 2017 tournament and had to withdraw from a honbasho for the first time in his career, bringing to an end his run of 739 consecutive matches from debut, the most among active top division wrestlers.

The March 2018 Tournament saw Kaisei promoted to East Maegashira #6 where he won his first 9 matches, only to lose to Ichinojo on day 10.

Fighting at maegashira 15 in July, he injured his right arm and eventually withdrew on Day 11 with only one win, resulting in his demotion to jūryō.

[13] Kaisei obtained Japanese citizenship in November 2014, which allowed him to acquire an elder-stock when retiring; he now uses the name Tomozuna oyakata.

The final cut was made by former ōzeki Kaiō, the master of the stable Kaisei transferred to after his retirement.

Kaisei's mother Rosana, younger brother Renato and sister Natalia made the approximately 30-hour trip from Brazil to Japan to attend the ceremony.

Sanshō key: F=Fighting spirit; O=Outstanding performance; T=Technique     Also shown: ★=Kinboshi; P=Playoff(s) Divisions: Makuuchi — Jūryō — Makushita — Sandanme — Jonidan — Jonokuchi