Sumire Tachibana

He just wanted to use the restroom!!

Here is what Google says:

""If you are talking about the relationship between someone and their grandma's sister's grandchild, the distance in relation would be considered a second cousin once removed; you share a great-grandparent with this person, making them your second cousin, and the "once removed" part signifies that there is one generation difference between you and them (your grandma's sister's grandchild is a generation below you).
Explanation:
Your grandma and her sister share the same parents (your great-grandparents).
Your grandma's sister's grandchild is the child of your great-aunt, making them your second cousin.
Since you are one generation above your grandma's sister's grandchild, they are considered "once removed"""

And there isn't much of a law to even prohibit marriage of second cousins once removed. Plus, they can't have offspring anyway. This isn't omegaverse. Plus, in most other countries, there are closer cousins that do marry. Consider this as "distant relatives". It isn't incest. Good grief.
Educate yourselves.