Ar, what a monster. He should be burned alive, but not to death, and then allowed to recover just enough so that he can fully feel all of the spikes of the iron maiden that closes on him as a manticore drips acid into his eyes.
Am i doing this right? I have no end of sympathy for your daughter, but I'm clearly not as vengeance-driven as you are. At some point in our past we decided that eye-for-an-eye was not a workable approach to justice and three lifetimes plus hundreds of years for an offense of twelve hours, no matter how awful those twelve hours may have been, goes so far beyond eye-for-an-eye... There's some horrible disconnect when it comes to sex crimes. We load down the act of sex with so much baggage that it's social anathema to do anything mildly sexually deviant, and crimes related to sex are seen as absolutely horrifying while doing relatively little physical / financial / property damage. There is of course the psychological aspect, which I by no means wish to trivialize, but I can't help but think that the psychological damage is made as severe as it is by all of the baggage which we attach to sex.
I have heard people say, without hyperbole, that they think that rape is as bad or worse than murder. Many rape victims also seem to feel that - 13% of rape victims attempt suicide. Think about that. These are people, a large number of people, who genuinely believe that it's better to be dead than raped. That's a problem, a big one, and it's a problem of perception. The courts only reinforce this, if they're handing down life-ending sentences over rape offenses, and that feeds the problem further.
Back to TFA: molestation isn't rape. Without reading the article, I'd guess based on the sentence that the offense of the guy in question was pretty small. Maybe a grope on the train or something, happens pretty often on those crowded Japanese commuter trains. Is that also worth murder?