This is one of the most phenomenal visual novels I've had the pleasure of experiencing. The plot is complex and not straight forward, and it changes depending on the route you take. Although very strong warning to future players. This game tugs at your heartstrings hard. There's a particular order I recommend playing the routes in.
Whatever you do, DO NOT PLAY WALTZ UNTIL YOU'VE COMPLETED THE OTHER ROUTES. I made that mistake and I strongly regret it.