Seigo Tachibana (立花 誠吾, Tachibana Seigo) is a Japanese professional wrestler working as a freelancer and is best known for his tenure with the Japanese promotions Wrestle-1 and All Japan Pro Wrestling where he also appeared under the ring names Masao Hanabatake (花畑 正男, Hanabatake Masao) and O Hanabatakemasa (花畑正 男, Hanabatakemasa O).

[3] Tachibana made his professional wrestling debut in Wrestle-1's W-1 Pro-Wrestling Training Academy 1st Graduation Class event on March 30, 2016, where he fell short to on of his coaches, Kaz Hayashi.

[5] Tachibana competed at W-1 WRESTLE-1 Tour Trans Magic, the last ever event hosted by Wrestle-1 on April 1, 2020, before its closure where he took part in a 31-man battle royal won by Manabu Soya and also featuring many of the promotion's roster figures such as El Lindaman, Cima, El Hijo del Pantera, Yasufumi Nakanoue, T-Hawk, Mazada and others.

He made his debut in the promotion at AJPW All Japan Pro Wrestling Wednesday Special on May 27, 2020, where he unsuccessfully challenged Yoshitatsu for the Gaora TV Championship.

[14] On the second night, Tachibana competed in a 13-man battle royal for a second chance to re-enter the tournament, match won by Tetsuya Endo and also involving Antonio Honda, Chris Brookes, Yukio Naya, Tomomitsu Matsunaga, Mad Paulie and others.