Urawa had given up top spot in the previous round and saw their winless run stretch to three matches on Saturday at the Kawasaki Todoroki Stadium.
Tsukasa Umesaki put the visitors in front with just two minutes on the clock, but Renatinho struck back almost immediately to restore parity.
The two sides remained level for more than an hour, but Frontale eventually moved ahead with 12 minutes to go, as Yoshito Okubo netted the winner to move Yahiro Kazama's men to within a point of the top two.
Urawa stay level on 37 points with Tosu, who are top on goal difference but surprisingly sacked coach Yoon Jung-hwan on Friday.
However, Tosu have a game in hand after their clash with Sanfrecce Hiroshima was postponed due to a typhoon.
Kashima Antlers remain within touching distance of the leading pack thanks to a late fightback at Nagoya Grampus.
Antlers went into the final 10 minutes 2-1 down, but goals from Davi and Yasushi Endo ultimately helped the visitors to claim victory and remain three points behind third-placed Frontale.
Gamba Osaka moved up to fifth courtesy of a 2-0 win at struggling Omiya Ardija, while Tokyo end the weekend in sixth after drawing 0-0 at Cerezo Osaka.
Rock-bottom Tokushima Vortis suffered a 14th defeat of the season, going down 1-0 at Shimizu S-Pulse, but Ventforet Kofu climbed up to 14th with a 0-0 home draw against Vegalta Sendai.
One of the day's more entertaining encounters saw Kashiwa Reysol come from two down to rescue a 2-2 draw at Yokohama F Marinos, with Daisuke Suzuki and Tatsuya Masushima finding the net for the away side.
Vissel Kobe left it late to defeat Albirex Niigata 1-0, Hiroyuki Komoto scoring in the 90th minute.
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