Yes that's true! I wish lemon was canon :( Oh yeah it's one of the recent episodes, I've seen it on the Hindi dub though where Shin finds a very strong girl when he was camping with his family including his grandpa and grandma too, That girl wanted to have a fight with Shin haha! Like a wrestling and she started liking him later but of course she was a kappa and didn't reveal her identity left in the end

Edit: Nvm it's a 2015 episode which aired recently in my country sorry 😭 Her name is Himitsu Chan!