I'm just gonna copy paste my reply here since I'm apparently the only one who brought it up or ever thought of it?
In the unlikely case Calix was main character's soulmate, Yeon's imprint would've glowed or became darker (something confirmed in the very first chapter) so there's no way it's Calix. Neither can it be his best friend as they would've noticed long by now. The long haired brunette is not on the manga cover because (It's my most rational theory) it's supposed to be a plot-twist, however if you analyze everything it makes sense.
- The main character's name is Yeon Soo Ha (Chapter 4, page 16).
- The long haired brunette's name is Go Hanbin (Chapter 7, page 64).
- GHB is Yeon's imprint and clearly stands for Go HanBin.
- YSH is Go's imprint and clearly stands for Yoon Soo Ha.
I believe this will be a story where main character will abandon the soulmate he's been waiting for all his life for the person he actually fell in love with (which can be either chef Calix or the best friend, and in my opinion this is a much better plot than Calix being his soulmate as it would be very monotone-ish, cliche-ish and boring. Props to the author if so!).
you're not the only one who has thought this - comments just get buried in this section because there are a lot of readers.
Omg :,( I feel so sad. This manga was sooo good and emotional. I can't believe that it ended. Guys, there are extra stories of eigyou nika! But nothing more. It ended production in 2015 which means that we won't have more </3. The author left a note
Okay wow. The cover of this manga is completely misleading because you would expect a story with very hot yaoi in it but what's hidden in it is actually deeper and more meaningful. I couldn't help crying a little with the end of chapter 3.. oh my god :,(
Please please please, consider translating "No Love Zone". It's a really good manhwa that was never picked up, sadly... It's really sad to think about :(