This is Meguro River Illumination called Megurogawa Minna no Illumination (目黒川みんなのイルミネーション) with lights on the sakura trees. The closest stations are Ōsaki Station and Gontanda Station on the Yamanote Line. It's about a six-minute walk from Ōsaki Station, which is the one I used.
Link:
Megurogawa Minna no Illumination New Energy Solution by CreativeOut
Viewing Megurogawa Minna no Illumination New Energy Solution at A' Design Award.