SEVENTEEN's Happy Ending topped Oricon's daily singles chart, Japan's largest music statistics site issued daily, weekly, monthly, and yearly by Oricon.

On May 29, 2019, the thirteen-member Kpop boy group released they're first Japanese single entitled "Happy Ending." Upon its release, the song took number 2 with 113, 201 units sold. A day after, the song made it to the top spot on the chart with 102, 090 units sold.

The day "Happy Ending" was revealed, it was also the same day when SEVENTEEN introduced their second mini album together with the other tracks such as the Japanese renditions of their songs "Oh My!" and "Healing."

SEVENTEEN's member Woozi wrote the new track along with Bumzu, Haru, and Robinson, and composed by Woozi and Bumzu. The physical release of "Happy Ending" comes in five versions; limited editions A-D and a Carat Edition Version. The song features less-bass heavy melody and guitar tune with the classic EDM tricks. The song is undoubtedly catchy, with members taking turns in singing "aishiteru" that one can find himself singing it for days.

On May 15, in an interview with SEVENTEEN, Woozi explained the difference between their previous album and their new single. He stated that their Japanese debut album "We Make You" was mainly showcasing the groups' energy, but this new single was created to send a touching message to Japanese Carats.

Woozi then explained how he ended up with the title "Happy Ending." And he answered that he was thinking about how to express the phrase "Let's always be together" in a newer way, and that was when the term "Happy Ending" came into his mind, which he believed that will allow people to imagine various things rather than just the phrase.

SEVENTEEN officially debuted in Japan on May 30, 2018, with their first Japanese mini album called "We Make You." On May 16 the same year, the music video for the album's lead single "Call, Call, Call!" was released.

The self-producing boy band's "Happy Ending" was not the only who topped the Oricon's chart but also their last Japanese song and album. After its release on May 30, "We Make You" ranked number 2 on Oricon's daily albums chart on the first day. It was also in second place on the weekly albums chart for the first week of June 2018.

Other than that, on June 9 the album took the number one spot on Oricon's daily albums chart for the very first time. They were able to sell 11,376 units, surpassing "Future" by J Soul Brothers from EXILE TRIBE.

Meanwhile, SEVENTEEN Woozi also mentioned in the interview that Japanese carats have always waited for their Japanese activities, so they have worked hard to make a great song like "Happy Ending," hoping that the song will touch many people's heart.