soulmate au where a soul mark appears somewhere on their body on their 21st bday and that same mark appears on their soulmates 21st bday aswell. lia and ryujin are dating prior to any of their soulmarks showing up. its now lias bday and she expresses her worry about their soulmarks not matching, ryujin reassures her (despite sharing that same worry) and they wait until ryujins bday. turns out they were soulmates and had nothing to worry about anyway