This is a Japanese room escape game, and as the title says, you got only 15 seconds which is not much. There are 21 endings in total. Good luck!
If you don't like timed games, you'd better play the slow-life version
Play Here (full version with time limit)
Play Here (slow-life version without time limit)
(Thanks Jack for the link )
Please use spoilers to give hints:
[spoiler=Title Here]Enter text here...[/spoiler]