Interesting idea... Do you need me to beta? I'll be happy to help...
You should write some more detail and explain how Shinichi was killed. It was also a little too fast-paced, you should slow down a bit. ^^
I like it so far, but there's lot you can do to improve.
If I'm being too critical, tell me!!
...I thought they were that size but weighed that much. I'm pretty sure... Well, I can change it. Oh, well, I think Kaito would be smart enough to figure out what happened... Missing handkerchief, being injured, witch... He's smart.