Nanatsuya: Shinobu no Housekibako

Shinobu, a second-year in high school, is part of the family that runs Kurata-ya, a storied pawn shop based in a breezy central Tokyo neighborhood. She helps run the place when school isn't calling, and she has a natural gift that aids her a great deal—the ability to see the "aura" released by gemstones! Shinobu doesn't have a boyfriend, but she does have a fiancé handpicked for her by her grandfather—Akisada Kitagami, a man from a prestigious family who wound up being taken in by Kurata-ya at a young age. He now works as a salesman for a first-class jewelry brand, but he's also got more than his fair share of secrets...

(Source: K Manga)