H1-KEY (하이키) is a girl group under Grandline Group. They debuted on January 5, 2022 with the release of the digital single "Athletic Girl".

The group currently consists of 4 members: Seoi (서이), Riina (리이나), Hwiseo (휘서), and Yel (옐). On May 24, 2022 it was announced that former member Sitala (시탈라) left the group due to personal reasons. On June 6, 2022 it was announced Hwiseo was added to the group.

The group had their first comeback on July 6, 2022, with their 1st Maxi Single Album "RUN" which features a title track of the same name along with 2 new tracks "Catch 'n' Release" and "Heart Light".

The group came back on January 6, 2023 with their 1st Mini Album "Rose Blossom" which features a title track of the same name along with 4 new tracks "Ring the Alarm", "Crown Jewel (feat. Tachaya)", "You Are My Key (for M1-KEY)" and "Dream Trip".

The group released the pre-release track "Time to Shine" on August 23, 2023, a few days before their comeback. They officially made their comeback on August 30, 2023 with their 2nd Mini Album "Seoul Dreaming" featuring the title track "SEOUL (Such a Beautiful City)" along with 3 new tracks "Low-key Scared But H1-KEY Ready", "Magical Dream" and the album intro "Intro : Seoul Dreaming".

The group went on to launch a music project titled H1-Keynote, subsequently leading to release of the digital single "Thinkin' About You" on January 19th, 2024. They would go on to release the 2nd single of the project titled "Deeper" on February 27th, 2024.

On June 19th, 2024, the group would release their comeback EP titled "Love or hate" which features the title track "Let It Burn" along with three new tracks "♥ Letter", "Iconic" and "Rainfalls". Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.