Manabu Tatsumura threw two touchdown passes and running back Shusaku Shiraki scored twice, leading the Obic Seagulls to a 35-14 triumph over the Fujitsu Frontiers on Monday in the X League action.
With the win, Obic (4-0) stayed undefeated in the East Division and secured a playoff berth with one regular season game to play.
The loss of the Frontiers (2-2) gave the Onward Skylarks (3-0) the other playoff berth in the division.
Playing before a crowd of 3,200 at Tokyo Dome, Obic showed a solid offense, possessing the ball for 30:59 in a 48-minute regulation.