Yellow is certainly similar to FAKE. Basically, instead of them being cops, they are snatchers xD! The relationships are also VERY similar. The art is gorgeous, the storyline is fine, and the characters from both are like twins =3! But warning, like in the last volume of FAKE, there is yaoi o.o
Yellow is like FAKE retold. In FAKE, one character is bi and he loves his partner who's straight (or, more appropriately, confused and/or doesn't realize it). In Yellow, one is gay, and you know the rest. There's a difference between the jobs (in FAKE, they're cops while in Yellow, they're 'drug snatchers' but what they do is pretty similar - they're sort of detectives ;^^) (Only, I found FAKE much better.)
Both manga are short. W/A is only 6 volumes and YELLOW is only 4. Both manga deal with drugs and yaoi undertones. YELLOW is explicit. W/A is definitely more implied but any yaoi-fan will be able to see and appreciate the beautiful relationship development.
Both are well-developed yaoi mangas with lots of action and mystery. Although "Yellow" is slightly more exciting and "Koujitsusei no Tobira" seems more like a slice of life story, at least in the beginning. But both are a very enjoyable read with a captivating plot.
Simply this: They are both amazing as ****. Emphasis on "amazing". Need more? Yellow here, is about two men, one proclaimed "straight" and the other "positively gay", who are typically employed by third parties to snatch drugs and miscellaneous from the mafia and private vendors. Game x Rush on the other hand, is about a bodyguard for hire who encounters a man who states his interest in the act of protecting clientele and would like to work for the company.
Certainly they don't sound too similar and in all truth, their basic concept is rather different as well, but they do both have that "must protect others" depth to them. And again, they are frankly just two addicting mangas that draw you in from chapter one. In addition to all that acting as a bonus, guess what? Yellow is, yes, a yaoi, and Game x Rush has underlying tones of shounen-ai that just simply never had a chance to live large.  read more
If you like the seme having to WORK for the affection of the uke, instead of the "short and sweet" romances, then Crimson Spell and Yellow are the ones for you ;)
(also had some GREAT humor, and pretty schmexy stuff thrown in ;)