Tsuna couldn't deny that he was an impossibility. Seven soulmates and counting. Seven different flowers that would appear, where they got scratched or bruised the vibrant plants would bloom, filling his life with color. As a child his mother would laugh, saying that indeed he did have some rowdy soulmates out there. Red and blue, shades of purple, bright yellow, he would follow his mother's example and place them in vases and put them on his windowsill.
"It's tradition." She'd say as she fixed a bouquet of anemones while Tsuna on the other side of the counter clumsily tried to make the small handful of hydrangeas and goldenrods fit together. "You keep them alive as a way of saying that you care for your soulmate the same way you care for their flowers. It's like saying you hope that whatever hurt they have gets better." Tsuna nodded and tried to stick the final hydrangea into the vase.
Tsuna was an impossibility not because he had so many soulmates. It may not be common, but it wasn't unheard of to have multiple soulmates. Sure the sheer number he had was irregular, but there were people with even more (despite how hard it was to believe that). No, the reason it should be impossible was the simple idea that anyone, least of all seven people, could be fatefully bonded with Dame-Tsuna. The older Tsuna got, the more it didn't seem right, didn't make sense. If anything he felt bad for them, that he would be a burden on them. He was half convinced that they would reject him (there are reports of that happening before. Many a night Tsuna would wander down that dark hole of the internet about soulmates who couldn't stand each other and how one would cast the other to the side. He didn't know if he could handle that seven times).
It was likely they were most, if not all, platonic soulmates. Surprisingly platonic soulmates were extremely common, especially in this day and age. Nana loved to see the see all the vibrant flowers lined up on the coffee table, she'd nudge Tsuna comment how lucky he was to have so many out there who would love him. He'd just nervously stare at them, never as sure as his mother was.