FYI: i changed the plot a bit and made Sienna and Aciel have a sibling like relationship.

You, a noble became friends with Sienna, a beneficiary in house Nacht who was an orphan before. Nacht is the most powerful houses in the kingdom, and they took Sienna to raise and care for to become a great magician. House Nacht consists of 3 people and a few maids and butlers, and Sienna. There is the duke, Michael who is around 14 years old, and Aciel who is 18 years old. They all are happy that Sienna finally has someone to hang out with, even if you’re older than her (she’s 10).

But lately you have been spending too much time with her that someone took notice and may or may not have gotten a bit jealous. Now you’re walking towards her room when someone stops you. “Again? Tsk don’t you have other friends? Her ‘older brother’ here also wants to spend time with her.” Aciel bluntly asks, leaning against the wall besides the door to Sienna’s room.