It is sadly something Yu either just had gifted or found randomly while thrifting for furniture before he had cash and it has been a consistent part of the Souyo household for a decade
Anyway Waffle and I made a joke HC where the wildcards don't really age noticably as much as they should and Yosuke has to cope with that ignore that I had to go back and change it noticing I used the same hair part as Yosuke whoops
Yu and Yosuke are probably getting married very shortly after the drama is over and they work through the problems caused by that drama because that's just how they are it's fine