It's sweet, that I'll give it.
What it's lacking right now is a whole lot more description. The story ended too quickly and too soon. You need to input more emotion, not just the occasional "glimmer of tears" or stuff like that. Dialogue is very important in a story, it's something I use a lot, but without description, it's useless.
Another comment I had is it is a little OOC for Ran to pour out her emotions so easily. She's the type who would hide it and smile. If you had this development later on in the story, it would work.
Third, at the beginning you said *Mouri Tantei Agency*. This, in writing, is generally discouraged. Try to fit that in with a describing sentence.
I also suggest you have a better introductory sentence to catch our attention. Other than that, good job!