Weird glitch ahoy XP
Here's a glitch I just found. It lets you go back in time.
No, I'm not going to say "using the Song of Time" so don't say "lol, u r dum u just play dat time song".
With this method, you can go from night of the first day to dawn of the first day, without losing any items and keeping any already started sidequests. So if you talked to Anju and got the keys, you will still be able to go into the top room. But the chest will still be empty at the same time.
To do this, go to Night of the First Day. Go to North Clocktown at 12:00. At about 12:30, Sakon will steal the old lady's bombs. Shoot him with an arrow. About one second after you shoot him, play the song of double time. It will ask you if you want to go to Dawn of the Second Day. Say yes. The screen will fade out as if to start the cutscene with the old lady, but you will then start the cutscene where you go forward in time. When that is over, you will be in North Clock town. Only difference is that it will be 6AM, Dawn of the First Day.
Why is this useful? No idea XD. It's just one of those weird glitches you can experiment with :P.