Tonight is Kim Hyun-joong's third Japanese single. There are five available versions of this single which has five completely different image concepts for each of the single covers. Each version includes different limited editions that may include a DVD with the music video to the three new songs.

On the first day of its release, Tonight single came up to second place right away with 101,818 copies sold, and taking the number two spot by the end of the week. The album received Gold certificate for selling more than 100,000 copies and has recently been certified platinum with 250,000 copies sold worldwide.

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