"Oh Sweet Days") is the thirty-fourth single by Japanese recording artist Ken Hirai.

[1] It was released on May 4, 2011 as the fifth single from Hirai's eighth studio album Japanese Singer.

[2] "Itoshiki Hibi yo" serves as theme song for the second season of the TBS drama Jin.

[1] The B-side, "Run to You" is used in Nexco Central Japan commercials starring actress Aya Ueto.

[7] "Itoshiki Hibi yo" was voted third most popular drama theme song of the spring season in a RecoChoku user poll.