User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-67.176.158.104-20140207023318/@comment-16281343-20140207114752

It's like this...

You have 100Hp. It will decrease until it reaches 50Hp and will not decrease unless killed which means from 50Hp straight to 0Hp. It will not go down to 49, 48, 47 but straight to 0.

When JD is used, it will constantly trim that Hp until it goes to 0.