Barairo Guardian

Kasuga Koharu is a small, "runty" type of girl who is forced to join "The Guardian Rose" by the club's director for her prestigious school. "The Guardian Rose" is a group that tends to the rose gardens on the grounds. Curious, Koharu goes to visit the garden, and upon arrival, she's surprised by the sight of a popular and smart young man dressed like a prince. His name is Jordan Kiriya, and sexual tension is sure to ensue!

(from mangaupdates)