Maseo Yamashiro was the Husband of the Samurai Katana. They had 2 kids and were childhood sweethearts. Katana picked Maseo over his brother, Takeo Yamashiro, and this angered him. Maseo and his family were later attacked by Takeo and Maseo was killed in the fight, along with the children. This caused Katana to start her superhero life.
Maseo Yamashiro first appeared in Batman and the Outsiders #11, created by writer Mike W. Barr and artist Jim Aparo.
Major Story Arcs
Maseo was later revived, along with Blowdart, Nunchaku, Shuriken, and Anthor Stoneaxe, out of the soultaker, which is what was used to kill him, so he was forced to help in a plot to kill Katana. He, and the rest of the revived warriors, had to fight the Outsiders on 2 occasions. He had to fight Katana twice, the first time forcing her to retreat. In the second battle he begged her to kill him and he was killed, once again by the soultaker. He the then returned back to the realm from which he was summoned.
Maseo was revived by a Black Power Ring, along with his children, who found and fought Katana, Halo, Creeper, and Killer Croc. He was eventually killed by Halo, who blasted him with light that the ring could not withstand.
The New 52
He was killed by his brother using the Soultaker Sword. As such, Maseo's soul is trapped in the limbo that resides within the sword. In Green Arrow #27, Katana is told by the mysterious blind man Magus that the death of Maseo is actually related to the secret society known as the Outsiders.
Maseo makes his live action debut in the CW TV series Arrow played by Karl Yune. During Oliver Queen's five year absence, he was captured by Amanda Waller and sent to live with Maseo, his wife Tatsu and their children. As a means of making Oliver stay put, she threatened Maseo and Tatsu's family as collateral. Maseo was tasked with training Oliver to be an ARGUS agent. After his son, Akio was killed by a biological attack on Hong Kong Maseo overwhelmed with guilt and grief found himself becoming a member of the League of Assassins as a means of running from his past. Present day Maseo is one of Ra’s al Ghul leading soldiers although he saved Oliver after being fatally wounded by Ra’s. He was killed by his former wife Tatsu in a sword fight.