A manga produced in Japan based on an American intellectual property was the top manga in the U.S. book channel according to information provided by NPD BookScan on sales from 12/31/17-1/28/18; RWBY, based on the animation produced by Austin-based Rooster Teeth (see "VIZ Developing ‘RWBY’ Manga"), topped all manga based on Japanese IP for the month.

Seventeen of the Top 20, including RWBY, were from Viz Media.  Kodansha’s Attack on Titan and two Seven Seas titles, The Ancient Magus’ Bride and Miss Kobayashi’s Dragon Maid, were the only non-Viz titles in the Top 20.
Check out the other Top 20 BookScan graphic novel charts from January:
January 2018 BookScan – Top 20 Adult Graphic Novels
January 2018 BookScan – Top 20 Author Graphic Novels
January 2018 BookScan – Top 20 Kids Graphic Novels
January 2018 BookScan – Top 20 Superhero Graphic Novels

And for the charts with the actual sales numbers from NPD BookScan, see these articles on our ICv2 Pro site:
January 2018 BookScan – Top 20 Adult Graphic Novels with Actual Sales
January 2018 BookScan – Top 20 Kids Graphic Novels with Actual Sales
January 2018 BookScan – Top 20 Manga Graphic Novels with Actual Sales
January 2018 BookScan – Top 20 Superhero Graphic Novels with Actual Sales
January 2018 BookScan – Top 20 Author Graphic Novels with Actual Sales

NPD BookScan Top 20 Manga - January 2018 (12/31/17 - 1/28/18)

Rank

Title

Author

Publisher

1

RWBY

SHIROW MIWA

VIZ MEDIA

2

DRAGON BALL SUPER VOL. 2

AKIRA TORIYAMA

VIZ MEDIA

3

TOKYO GHOUL: RE VOL. 2

SUI ISHIDA

VIZ MEDIA

4

MY HERO ACADEMIA VOL. 10

KOHEI HORIKOSHI

VIZ MEDIA

5

MY HERO ACADEMIA VOL. 1

KOHEI HORIKOSHI

VIZ MEDIA

6

TOKYO GHOUL: RE VOL. 1

SUI ISHIDA

VIZ MEDIA

7

ATTACK ON TITAN VOL. 23

HAJIME ISAYAMA

KODANSHA COMICS

8

BLUE EXORCIST VOL. 18

KAZUE KATO

VIZ MEDIA

9

SHIVER: JUNJI ITO SELECTED STORIES HC

JUNJI ITO

VIZ MEDIA

10

SPLATOON VOL. 1

SANKICHI HINODEYA

VIZ MEDIA

11

MY HERO ACADEMIA VOL. 2

KOHEI HORIKOSHI

VIZ MEDIA

12

TOKYO GHOUL VOL. 1

SUI ISHIDA

VIZ MEDIA

13

THE LEGEND OF ZELDA: TWILIGHT PRINCESS VOL. 2

AKIRA HIMEKAWA

VIZ MEDIA

14

DRAGON BALL SUPER VOL. 1

AKIRA TORIYAMA

VIZ MEDIA

15

MY HERO ACADEMIA VOL. 9

KOHEI HORIKOSHI

VIZ MEDIA

16

THE LEGEND OF ZELDA: TWILIGHT PRINCESS VOL. 1

AKIRA HIMEKAWA

VIZ MEDIA

17

ONE-PUNCH MAN VOL. 1

ONE

VIZ MEDIA

18

MY HERO ACADEMIA VOL. 3

KOHEI HORIKOSHI

VIZ MEDIA

19

THE ANCIENT MAGUS' BRIDE VOL. 1

KORE YAMAZAKI

SEVEN SEAS

20

MISS KOBAYASHI'S DRAGON MAID VOL. 1

COOLKYOUSINNJYA

SEVEN SEAS

Source: The NPD Group/BookScan

NPD Bookscan collects weekly point-of-sale data on print books from over 16,000 locations including e-tailers, chains, mass merchandisers, independent bookstores, and more.  NPD Bookscan covers approximately 85% of the U.S. trade print book market.  The ranks on this chart are based on piece sales. Some publishers classify titles that are primarily text, or art books, as graphic novels; we've removed those titles from the ranking above.

For past BookScan Top 20 Graphic Novel lists, see the "BookScan Top 20 GN Index."