Stunned by a Japanese wake

My friend Mike is currently teaching English in Japan. Recently, his landlord passed away. So, he attended the landlord’s wake, which was the first time for him to attend a Japanese wake. When he arrived at the venue, there was something unexpected: merrymaking. Everyone was eating sushi, drinking sake, and making noise. “They're supposed to be sad, but drunk and having a good time instead? I can’t believe it.…" Mike was stunned.

Unable to understand their merrymaking, he asked for my insight. But I didn’t get it either because I had once annoyed people at an acquaintance’s funeral by being cheerful during the photo session taking a commemorative photo of all the attendees. I accidentally smiled at the moment the photographer pressed the shutter button. It was just a habit.... Anyway, how come it’s okay to have a "bacchanal” at a wake while my smiling was a big no-no?

It’s a mystery to me although I’m from Japan. Then, how can I explain to Mike, who is American? After thinking about endless possibilities, I made up a reason: “The deceased must have liked festivities. He’s glad to see everyone else is having fun. So, everything is all right." Mike still seems to be bewildered….