Hiroshima finished the 34-game campaign with 63 points, one clear of Yokohama. Kawasaki (60) clinched third place. The top three teams qualify for next season's Asian Champions League.
Hiroshima got a break when Kawasaki striker Yuya Osako was booked for the second time and sent off after a foul on Tsukasa Shiotani late in the first half.
In other matches, Yoichiro Kakitani scored twice as Cerezo Osaka trounced Urawa Reds 5-2 to secure fourth place. Kashima placed fifth and Reds sixth.
Nagoya Grampus lost 2-0 to Albirex Niigata in manager Dragan Stojkovic's last game in charge while FC Tokyo won 2-0 over Vegalta Sendai and Omiya Ardija edged relegated Shonan Bellmare 1-0 away.
Kashiwa Reysol beat Shimizu S-Pulse 2-1 and Jubilo Iwata downed Oita Trinita 3-1 in a showdown between the bottom two teams. Ventforet Kofu against Sagan Tosu finished in a goalless draw.