Wondering what tag should be for artist currently with the e621 tag sleepy_(artist)
(tag probably chosen because Tumblr has "SLEEPY" at top with "ABOUT "SLEEPY"" a main link at top of that Tumblr
but that Tumblr also says "© 2020 goodnight".

(EDIT: and Sleepy_(artist) also doesn't seem like a good tag because there are other artist tags that start with Sleepy. See Endnote.

Artworks by the artist uploaded to e621 are: post #907392 and post #907389 )

The only artwork with artist name on it seems to be
https://good9ight.tumblr.com/post/190869975947/skeb%E3%81%AB%E3%81%A6%E3%81%94%E4%BE%9D%E9%A0%BC%E3%81%84%E3%81%9F%E3%81%A0%E3%81%84%E3%81%9F%E3%82%82%E3%81%AE%E3%81%A7%E3%81%99-httpsskebjpworks45434
which seems to say "good night" (with space) around hand near bottom-right corner.

1) So artist tag could be good_night_(artist), so as to not be confused with general tag good_night

or
2) artist tag could be goodnight_(artist), since name at pixiv is "goodnight" https://www.pixiv.net/en/users/4170728
and Tumblr says "© 2020 goodnight".

or
3) artist tag could be good9ight,
but that seems more a username at Tumblr and Twitter than artist name.
( https://good9ight.tumblr.com/
https://twitter.com/good9ight )

* * * * * * * * * * * *

EDIT: Just noticed twitter 'name' is currently "ʇɥƃıupooƃ"" ("goodnight", but upside down).
So learning towards tag being goodnight_(artist) (combination of name at twitter, name at pixiv, and Tumblr saying "© 2020 goodnight")

ENDNOTE
Sleepy* artist tags (via e621 tag search )

sleepy_* artist tags (and a sleepy-* tag):
12 . . . sleepy_acorn
5 . . . sleepy_artist_(artist)
2 . . . sleepy_buck
1 . . . sleepy_coco
1 . . . sleepy_kettle
1 . . . sleepy-mia
2 . . . sleepy_screen_(artist) (merge with sleepy_screen) ?
1 . . . sleepy_sealion

and other sleep* artist tags:
1 . . . sleepyalbus
1 . . . sleepybunno
1 . . . sleepybutler
2 . . . sleepybytes
1 . . . sleepychi
1 . . . sleepychu
1 . . . sleepyface
7 . . . sleepygills
1 . . . sleepygimp
9 . . . sleepyhelen
1 . . . sleepykirin
1 . . . sleepykit
1 . . . sleepyknight
1 . . . sleepykun
1 . . . sleepykweenowo_(artist)
1 . . . sleepylugia
32 . . . sleepymaid
1 . . . sleepymei_(artist)
69 . . . sleepymomo
2 . . . sleepymonster
15 . . . sleepymute
1 . . . sleepynerd_(artist)
5 . . . sleepynu
1 . . . sleepyoldvamp
1 . . . sleepypyromancer
23 . . . sleepyras
1 . . . sleepyredwolf
3 . . . sleepyree
1 . . . sleepyrythm
8 . . . sleepyscientist
19 . . . sleepyscreen
25 . . . sleepysealion
12 . . . sleepysheep
3 . . . sleepysuika
14 . . . sleepytea
2 . . . sleepytiger
35 . . . sleepytoy
1 . . . sleepytroll_(artist)