A few days ago in the game, in winter, I got the 10 hearts with him and unlocked the diamond ring. The thing is that 3-4 days have passed in the game and I don't get the letter from Wakuu to be able to see the event ;; And I already have the house, the ring ready....
#Wakuu's 10 heart event
mortal urchin
last heath
Wait until Spring, it seems like it doesn't trigger in Winter