According to Cluley, the case is the first in Japan, where officials used property destruction charges when prosecuting Masato Nakatsuji.
Nakatsuji created the ika-tako (squid-octopus) malware, which was spread via the Winny peer-to-peer file-sharing network between May and July of this year and says Cluley, replaced the affected files with an image of an orange cartoon octopus.
"That’s not the kind of thing which is looked on kindly at the best of times, but what makes the case look worse for Nakatsuji is that he has previous convictions for cybercrime", the Sophos consultant says in his latest security posting.
"Back in 2008, Nakatsuji became the first virus writer ever arrested in Japan after distributing the Pirlames Trojan (dubbed Harada in the local press) via Winny that displayed images of popular anime characters while wiping music and movie files", he adds.
Cluley went on to say that Nakatsuji was found guilty of violating copyright laws by spreading the anime images and given a two year suspended prison sentence.
Incredibly, Nakatsuji reportedly wrote his new `ika-tako' virus while on probation for the previous offence.
"Finding Nakatsuji guilty of destroying data on victims' computers in the latest incident, Judge Masaru Okabe of Tokyo District Court said that he had no choice but to hand out a custodial sentence," says Cluley.
"It was an ingenious, planned crime to spread a computer virus over a long period of time. The defendant committed the crime while he was on probation for a similar charge. I have no choice but to give him a sentence without suspension", said the judge in the case.
The Sophos consultant notes that Japan is currently in the process of passing a set of laws that makes virus writing illegal.
"Once again, it's clear that some people have not got the message that malware is not a fun game, but can have serious consequences. Maybe Masato Nakatsuji's spell in prison will give him time to reflect on that, he says.