which doujins have the biggest boobs?

So many to choose... try just looking for them in the manga section 75% of the manga here was BIG ASS TITTY's.

Mogudan's current art-style focuses on big tits, ass and thighs try giving that a whirl.

If you're look for massive Send a Private Message asking this guy.

https://www.fakku.net/users/kawaiiloli

or this guy

https://www.fakku.net/users/Zzelos

Big boobs though are fairly common and should be easy to find. Anything specific and I might have it to give to you.

anything non-loli

While not doujinshi, G-Cup Reiko has the largest boobs I've seen that are actually still appealing.
g/33014/2d2498d93c/


The absolute biggest I've seen is from Blue Eyes, however, but those are just freakish and disturbing.
g/1413/bb9fbef8be/

Something that immediately comes to mind is Kyonyu Alpha by Wakatsuki. I love his art.





Tetsujinex has some amazing stuff if you like them massive:
https://www.fakku.net/viewtopic.php?t=35753
https://www.fakku.net/viewtopic.php?t=42450

Other artists to note:
Mogudan
Takaoka Motofumi
Yunioshi
Youshu Ohepe
INSERT
Nico Pun Nise
DISTANCE
Sakaki Utamaru
Norutaru
NewMen
Ando Hiroyuki
Amatarou
Yamamoto Yoshifumi
Yumisuke Kotoyoshi
Erect Sawaru
PEN Gindou
Jamming
Haru Wamusato
E-Musu Aki
Kensoh Ogawa
Jingrock


That's probably enough for now, no? There are more, but I have yet to compile an extensive list. :P