After their breakthrough in 1994, Mr. Children yielded eight consecutive chart-topping singles. Three of those hits were appeared on the album; "Na mo Naki Uta", "Hana (Mémento-Mori)", and "Machine Gun o Buppanase" — while others were reserved for their subsequent release Bolero in 1997.

Kazutoshi Sakurai, a chief singer-songwriter of the band named the album's working title as Coelacanth (シーラカンス, Shīrakansu), which was misheard by his band-mate as "Shinkai" (lit. "deep sea"). Sakurai, who favored the sound of the phrase, decided to change the title of the album.

Shinkai was a sort of concept album, featuring more insightful compositions and harder-edged sound compared to the band's previous materials. The whole album is played gaplessly, though each tracks are separated on CD. They had not anticipated that such an adventurous effort would be a big hit.

Contrary to the group's prediction, Shinkai met with commercial success, although it underperformed its predecessor in cumulative sales. It debuted at number one on the Japanese Oricon chart with first-week sales of over 1.5 million copies, becoming the country's fastest selling album at the time. The album spent 46 weeks on the top 100, selling over 2.7 million units during its chart run. Upon its release, Shinkai was certified double-million by the Recording Industry Association of Japan, for shipments of over 2 million copies.

All tracks written by Kazutoshi Sakurai, arranged by Takeshi Kobayashi and Mr. Children.

^{^}shipments figures based on certification alone

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