Leicester City 1 Brighton 0
The Japanese international rose well at the far post to head past Casper Ankergren just after half-time following some great hold-up play by Darius Vassell in what proved to be the decisive moment in the game.
Craig Mackail-Smith inexplicably volleyed over from six yards for the away side before Marcos Painter was sent off for a second bookable offence after handling the ball.
Both sides had chances to score but Leicester held on for the three points; a win which pushed them up to ninth in the Championship and subsequently knocked Brighton off the top of the table.
The Foxes have now won consecutive home games for the first time this season, and manager Sven Goran-Eriksson will have been delighted with his side's work rate in the second-half.
It was Brighton who started the game strongly, however, and could have taken the lead through Craig Mackail-Smith, but his unmarked header fell straight into the hands of Leicester goalkeeper Kasper Schmeichel.
But against the run of play, Leicester inexplicably had a goal disallowed when Lee Peltier fired past Ankergren - but Darius Vassell was adjudged by referee Graham Scott to have been fouled in the build-up, despite there being a clear advantage to the home side.
Paul Konchesky fired the subsequent free-kick into the wall but the passage of play seemed to spark Leicester into life, with Andy King's fierce strike forcing Casper Ankergren to make a good diving save.
As the half progressed, Brighton looked the side more likely to break the deadlock - but five minutes before the break, Sol Bamba tested Ankergren with a downward header from Richie Wellens' corner; the ball bouncing before the former Leeds shot stopper did enough to tip it over the bar.
Matt Mills also headed over and Andy King fired wide from 25 yards in a relatively forgettable first-half in which the hosts lacked any real creativity, although did match their counterparts in terms of solid defending.
Leicester were ahead less than a minute after the restart when Darius Vassell made space for himself on the left side, avoiding two Brighton defenders, before playing a fantastic ball to the back post where Yuki Abe was unmarked to fire home a strong header past the helpless Ankergren.
It was Abe's first goal of the season in which he had featured irregularly to date, but wonderfully worked by the former England international Vassell and a fantastic start to the second-half for Sven-Goran Eriksson's men.
Brighton should have been level minutes later, however, when Ashley Barnes picked out team-mate Craig Mackail-Smith in the Leicester penalty area, but the front man somehow cleared the crossbar from less than six yards out.
New signing Jermaine Beckford had been kept quiet in the first-half, but began to impress in the second on 55 minutes by passing two Brighton players before setting up Gelson Fernandes, who fired over.
Beckford then tested Ankergren with a shot from distance to which the goalkeeper was equal, before Darius Vassell hit the side netting from a tight angle as Leicester pushed for a second goal.
Leicester continued to terrorise Brighton with their pace up front as Darius Vassell had another goal bound shot blocked, but Gus Poyet's side nearly found a way back into the game when substitute Will Buckley picked out Ryan Harley just inside the Leicester penalty area - but Lee Peltier and Matt Mills did fantastically to thwart the midfielder's efforts with two great blocks.
With ten minutes remaining, Brighton were then down to ten men when Marcos Painter received a second booking for a deliberate handball, which appeared to deflate the away side in their quest for an equaliser.
As time ran down, Jermaine Beckford fired over and Schmeichel parried away a dangerous cross by Kazenga LuaLua - but the home side held on comfortably to take an important three points.
Sven-Goran Eriksson will feel his side did enough to win the match against a side who had been flying so far this season, and will take confidence from the work ethic from all of his players to keep a clean sheet - Leicester's first since the opening day of the season.