Let's solve the Showa retro mystery!

[Recommended for these people]
People who want to kill some time, people who have time to wait for a train
People who like puzzles, people who like brain exercises
People who like Showa retro, people who like solving mysteries
It comes with auto-save hints, so it's recommended for beginners!
The difficulty level of solving the puzzles is easy, so I think you can solve them quickly.
Please come and kill time!