Sacramento Kings Rookie -- I've Got a Hello Kitty Backpack ... AND I MAKE IT LOOK GOOD!

Sacramento Kings rookie Ray McCallum Jr. says he hasn't just come to terms with the bright pink "Hello Kitty" backpack he's gotta carry around ... HE'S PROUD OF IT!

RMJ was heading toward the team bus in NYC over the weekend when our photog was blinded by the pinkness -- and Ray explained why he and fellow rookie Ben McLemore are obligated to rock the look.

That's when Ray started braggin' about his backpack -- and said his bag was BETTER than Ben's.

Ben strolled by with his bag a few minutes earlier ... but didn't wanna talk about it.

Seems like someone's got a case of bag envy.