The theme song for the Tsuyoshi Kusanagi-starring medical drama 37-sai de Isha ni Natta Boku: Kenshui Junjō Monogatari, it was released as a single by the band in May 2012, the first from their sixth album Sakanaction.

The song's music video was recorded live in a single take, featuring Yamaguchi as a "delicate-hearted" protagonist dancing with choreographer Yoko Honaga playing a flower spirit.

[1] The album was strongly affected by the events of the 2011 Tōhoku earthquake and tsunami which had occurred in March of that year, during the promotional period for their single "Rookie".

[9] When they received the offer, the band had been working on "Yoru no Odoriko" (2012), a song commissioned to appear in commercials for the design vocational school Mode Gakuen.

[7] After the writing and discussion process was finished, pre-production for the song began in mid-February, and recording was completed in March 2012,[10] approximately a month before the drama would begin to air.

[11][12] On March 28, the band released a video album for their October and November 2011 tour, Sakanaquarium 2011 Documentaly: Live at Makuhari Messe.

[10] Okazaki also used Fantom-G keyboard's pipe organ sound suite, the second time she had done this after "Bach no Senritsu o Yoru ni Kiita Sei Desu" (2011).

[10] Originally she intended to perform this section on a real pipe organ, but found that the Fantom-G's rotary effect suited the song better.

[17] It was the first experience for Yamaguchi to have someone telling him to alter his lyrics, however he did not object to the request, as he felt that "Boku to Hana" was a composition that would not have existed if not for the drama.

[17] "Boku to Hana" is a medium tempo pop song, performed with rock instruments sound that incorporates electronic elements.

[10] The single's announcement was less than two weeks before the first episode of 37-sai de Isha ni Natta Boku: Kenshui Junjō Monogatari aired on April 10.

"Neptunus" was written in the same lyrical world view as "Boku to Hana", as the band had done on their previous single "Bach no Senritsu o Yoru ni Kiita Sei Desu" with its B-side "Years".

[10] The band decided to include a remix by Ishino after considering what sort of music would be the best for the people who grew to know "Boku to Hana" because of its use as a drama theme song.

[31] The concert, Sakanaquarium 2012: Zepp Alive, was released as a live album on November 14, 2012, featuring performances of both "Boku to Hana" and its remix.

[32] The remix was created to be how the band would have performed "Boku to Hana" if it had not needed to be a pop song intended for a wide audience of drama viewers.

It depicts a television programming guide listing 37-sai de Isha ni Natta Boku: Kenshui Junjō Monogatari, on top of which stands drawn characters, who represent the band members of Sakanaction.

[26] Hatos' designer Kamikene was inspired to create the artwork by considering Sakanaction writing a television drama theme song as a challenge for them to enter mainstream media.

[23] The video begins with the protagonist sitting alone in a room, while a "flower spirit", played by dancer and choreographer Yoko Honaga, dances around him.

As he moves, the protagonist encounters obstacles he tries to save the pot plant, such as dancers dressed as train commuters, or the flower being blown away.

[48] This made "Boku to Hana" the band's most successful song on the chart to date, beating out "Aruku Around" (2010) and "Bach no Senritsu o Yoru ni Kiita Sei Desu"'s (2011) positions of 38 and 30 respectively.