Career
He lost the title three months later in his first defense against Miguel Canto. In 1976, Oguma challenged WBA Flyweight Title holder Alfonso Lopez but lost a majority decision. In 1978 he landed a rematch with WBC Flyweight Title holder Canto but came up short with a split decision loss.
Later that year he fought his third bout with Canto, and this time lost a more clear unanimous decision to complete their trilogy.
In 1979 he rematched WBA Flyweight Title holder Gonzalez and the result was a draw. Later that year they fought a rematch and Gonzalez came up with the victory via a 12th round KO in their third match.
In 1980 Oguma landed a shot at WBC and The Ring Flyweight Titles holder Chan-Hee Park and KO"d Park in the 9th round to capture the titles. He then moved up in weight and in 1982 took on WBA Super Flyweight Title holder Jiro Watanabe, but was TKO"d in the 12th.
Oguma retired after the bout.