BTS's 'MIC Drop' is a single which sold 453,721 copies. It is 1st in sales, 2nd in look up, 65th in downloads, 4th in Twitter, 24th in mv views. It leads 'JAPAN HOT 100' with a big difference in physical sales from below the 2nd placer.
NGT48's second single 'Sekai wa Doko Made Aozora na no ka?' is a single which sold 202,323 copies. It is 2nd in sales, 6th in look up, 45th in downloads, 9th in Twitter, 19th in radio airplay, it also increased in its physical sales, but wasn't able to match up with BTS, thus, ranked 2nd over-all.
BTS's surge is great that in the Top 20 we have 'MIC Drop' (over-all 1st), 'DNA' (over-all 10th), 'Crystal Snow' (over-all 19th), all 3 songs accomplished brilliant achievements. 'DNA' and 'Crystal Snow' didn't have singles sales points, but were heaped up with download, streaming, Twitter, mv views' digital domain points. Similarly with their break in the US, they became [artists] being greatly noticed here in Japan too.
Utada Hikaru's 'Anata' is in its first entry this week. 1st in downloads, 15th in radio airplay, 19th in Twitter, 59th in mv views. Although the points are raised by each indicator, with the download points by far, it became 3rd over-all. Furthermore, the one who prevented BTS's Twitter top position was the long awaited first step restart, TVXQ's 'Reboot.' Approximately by Twitter points it ranked 18th which is its first entry as before its release on 12/20, the anticipation of the core fans has also quickly risen up.
T/N: I added this guide to further understand how Billboard Japan Hot 100 works
Billboard Japan Hot 100
1. estimated sales figures nationwide (real stores, convenience stores, online), download count (iTunes Jpn, amazon, Google Play Music, mora, mu-mo, recochoku), streaming play count (Apple Music, AWA, Google Play Music, KKBOX, LINE MUSIC, Rakuten Music, recochoku)
2. AM/FM radio plays
3. number of times a CD is read into a computer (look-up)
4. number of times the song and artist's name was tweeted
5. number of video plays (YouTube, GYAO!)
Over-all points for 171218 (JPN chart date) the one which will reflect in Billboard US webpage for 171223
MIC Drop = 28,938 points
DNA = 2,477 points
Crystal Snow = 1,823 points
Billboard Japan data uses SoundScan Japan data which is different from Oricon Charts.