One Drop (KAT-TUN song)

"One Drop" is the sixth single released by Japanese pop band KAT-TUN. It was released on February 4, 2009, by J-One Records. The single was released in three versions: a limited edition with a DVD containing the music video and making-of footage, a first press edition with a bonus track ("On My Mind"), and a regular edition with instrumental versions of both "One Drop" and the B-side track "White X'mas".

The title track, "One Drop," was used as the theme song for the Japanese television drama Kami no Shizuku (神の雫, "Drops of God"), starring KAT-TUN member Kazuya Kamenashi. The lyrics of the song revolve around themes of trust, betrayal, and the complexities of human relationships, mirroring the drama's storyline. "White X'mas," the B-side, is a winter-themed ballad, contrasting with the rock-infused sound of "One Drop."

"One Drop" debuted at number one on the Oricon weekly singles chart, selling over 290,000 copies in its first week. It went on to be certified platinum by the Recording Industry Association of Japan (RIAJ) for shipments of over 250,000 copies. The song remains one of KAT-TUN's popular tracks and is frequently performed at their concerts.