While hinting at new music for 2020, the ballad "365" hits tops the chart in one of the quickest ascents among K-pop groups.

LOONA are closing out the decade on top.

In the final charting week of 2019, the 12-member K-pop girl group earn their first No. 1 on Billboard's World Digital Song Sales chart this week with new song "365," topping the chart dated Dec. 28, 2019. The track beats LOONA's previous peak on the chart set by their very-first chart entry as a group when "favOriTe" entered at No. 4 in August 2018.

LOONA has since landed two more top 10 entries, both earned earlier this year with "Butterfly" (which peaked at No. 6 in March this year) as well as their previously released track "The Carol" (which rose back into the tally after a fan-driven holiday push, letting it debut at No. 5).

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"365" tops World Digital Song Sales just under a year-and-a-half after LOONA's debut which makes them one of the fastest K-pop groups to hit the summit. LOONA is the fourth-quickest act to hit No. 1 on World Digital Song Sales among all K-pop acts and third quickest among K-pop girl groups.

Take a look at the five fastest ascents to No. 1 among K-pop acts below, keeping in mind that, historically, time lengths between album releases and when charts are dated have varied throughout Billboard history:

Artist, Single Title - Time from debut to No. 1 position

1. Tomorrow X Together, "Crown" - 12 days

2. BLACKPINK, "Boombayah" - 19 days

3. (G)I-DLE, "Pop/Stars" with Madison Beer and Jaira Burns - 6 months, 15 days

4. LOONA, "365" - 1 year, 4 months and 8 days

5. TWICE, "Likey" - 2 years and 28 days

Notably, a ballad like "365" is a stark change-up from LOONA's usual synth-pop treats that's been key in helping them garner a large international fanbase. Still, the track's impressive chart performance indicates big moves could be on the way for LOONA as the group has already begun hinting at more music coming soon with mysterious videos like the "#1" visual that sees member Heejin floating above clouds amid stark, atmospheric background music.

Stream "365" below and look out for more from LOONA soon.