Currently, we have no intention of breaking change of the API,
but if people use this library, they might request it,
and we hope it happened to sophisticate the API.

We expect binary format of the Docchi and History files will be changed
in the near future for the loading process to be more concurrent.

Needs to improve removing process to be durable for sudden power outage.

Currently, we are creating a sample game, 
which is a Ninja TRPG simulator, to prove this library can be used smoothly.