He retired from active competition in 2010 and became a coach, but in April 2011 he was asked to resign from the Japan Sumo Association after being found guilty of match-fixing.

At this point he switched from fighting under his family name of Kumagaya to the shikona of Kaihō, which was taken from the name of his father's boat, Kaihō-maru (Kai means "ocean" or "sea" in Japanese).

He stayed in the top division for the next 44 tournaments with just one brief demotion to jūryō in November 2003, and won his second special prize in March 2005 after a fine 11-4 record.

He remained there until July 2007, when, due to the unusually large number of retirements and demotions from the top division, a 9-6 score at jūryō 5 was good enough to return him to makuuchi.

He produced a strong 10-5 record in his first tournament back in the top division, and although he missed out on another special prize he was promoted up the rankings to maegashira 6.

"[3] Following his retirement Kaiho became certified as a kaatsu instructor and opened his own gym in Tokyo, where he trained some wrestlers active in professional sumo such as Hidenoumi.

[6] Kaihō was below average size for a rikishi and relied on his technical ability, employing a similar sumo style to Mainoumi.

He was known for often employing henka, or sidestepping at the tachi-ai or initial charge, and was adept at using inashi, or ducking and moving diagonally back from the opponent.