help me find this manhwa

historical bl. the mc bottom (manly uke, dark haired) is half demon half noble who prides himself for being the best in the military academy. but then his junior (tall blonde tree) who he help before, overtook his place. jealous and bitter, he summond and formed a contract with a demon acquaintance who needs to find the junior's weakness in exchange for sex (sustenance). demon acquaintance did his job, finds out that the weakness is the mc (seme has a crush on him) and exploited it to get more sustenance. by blindfolding uke and luring seme into his room to feed on his fantasies. they had threesom.

its a short one. with vague ending.