Billie Eilish and Finneas O'Connell pose in the press room with the awards for Album Of The Year, Record Of The Year, Best New Artist, Song Of The Year and Best Pop Vocal Album during the 62nd Annual Grammy Awards on Jan. 26, 2020, in Los Angeles.

J-pop girl group STU48's fourth single, "Mubou na yume wa samerukoto ga nai" -- which loosely translates to "reckless dreams never end" -- sold 332,691 copies in its first week to debut at No. 1 on the latest Billboard Japan Hot 100, dated Jan. 27 to Feb. 2.

The group's new single sold more than its previous release and broke its personal sales record, coming in at No. 1 for physical sales this week. However, the relatively new girl group still has room for improvement in the other metrics of the chart's methodology -- No. 11 for look-ups, No. 15 for radio airplay, and No. 16 for Twitter mentions -- and apparently needs a bit more time to expand its reach outside of its core fanbase.

News of young Billie Eilish winning the top four categories and more at the 62nd Grammys made headlines in Japan last week, significantly boosting her popularity in the country. Her Grammy-winning single "bad guy" soared to No. 1 on radio airplay and also rose to No. 4 for video views, No. 5 for downloads, and No. 7 for streaming, lifting the song 21-7 on the Japan Hot 100. It's been 37 weeks since a Western artist last broke into the top 10 on the list: Ed Sheeran and Justin Bieber's "I Don't Care" hit No. 10 on the chart dated May 27 last year.

SixTONES' "Imitation Rain" and Snow Man's "D.D." took the top two slots on the Japan Hot 100 last week with the former leading the tally, but the positions by the two new Johnny's boy bands are reversed this week with "D.D." at No. 4 and "Imitation Rain" at No. 5. Snow Man's single sold 7,351 more copies this week and its music video was viewed 359,984 more times, while SixTONES performed better in radio, look-ups, Twitter, and karaoke, but not enough to overturn the differences. Both songs are already racking up points in karaoke, meaning the songs are becoming familiar to the general public.

King Gnu's "Hakujitsu" returns to No. 2 as it continues to rule streaming for the third consecutive week. While it's losing points slightly in other metrics, overall, the song is still going strong, and has a chance to become the band's first No. 1 song in the coming weeks.

The Billboard Japan Hot 100 combines physical and digital sales, radio airplay, Twitter mentions, YouTube and GYAO! video views, Gracenote look-ups, audio streams from Amazon Music Unlimited, Apple Music, AWA, Google Play Music, KKBOX, LINE MUSIC, Rakuten Music, RecMusic provided by Gfk Japan, dHits, Uta Pass and Spotify, plus karaoke data from Daiichikosho and XING.

Billboard Japan Hot 100 Top 10 (dated Jan. 27 to Feb. 2)

1. [-] Mubou na yume wa samerukoto ga nai / STU48 (332,691 copies / none / none)

2. [4] Hakujitsu / King Gnu (none / 17,716 downloads / 6,883,052 streams)

3. [5] Pretender / Official HIGE DANdism (none / 16,615 downloads / 6,483,403 streams)

4. [2] D.D. / Snow Man (43,505 copies / none / none)

5. [1] Imitation Rain / SixTONES (36,154 copies / none / none)

6. [7] I LOVE… / Official HIGE DANdism (none / 25,307 downloads / 4,974,277 streams)

7. [21] bad guy / Billie Eilish (none / 15,954 downloads / 3,707,790 streams)

8. [9] Gurenge / LiSA (1,985 copies / 15,676 downloads / 3,829,746 streams)

9. [10] Machigaisagashi / Masaki Suda (none / 9,131 downloads / 3,347,693 streams)

10. [8] Teenager Forever / King Gnu (none / 6,174 downloads / 3,981,883 streams)

[ ]: Position last week

( ): Physical sales / downloads / streams (Top 50 only)