Before his sporting career ended in late 2006, Obata trained as part of the men's freestyle wrestling squad at Yamanashi Gakuin University under his coach and mentor Yuji Takada.

Obata emerged into the global spotlight by taking home the bronze medal in the 76-kg division at the 2001 Asian Wrestling Championships in Ulaanbaatar, Mongolia.

He also entered the 2002 Asian Games in Busan, South Korea as one of the heavy medal favorites in the middleweight category, but left empty-handed with a seventh-place finish.

[2][3] He easily ousted India's Sujeet Maan on his opening match 8–0, but could not resemble a scoring margin to turn down Cuba's Iván Fundora on the mat in his second bout.

[4][5] At the 2006 Asian Games in Doha, Qatar, Obata notched a pair of two easy victories in the same tournament, but could not score enough points to dismantle Uzbekistan's Soslan Tigiev for the bronze medal 0–4, dropping him to fifth.