A Japanese man has been accused of a bizarre virus attack in which files on infected PCs were destroyed before having their file icons replaced with manga-like drawings of sea creatures.

According to Japanese site, Asahi.com, the Ikatako (‘squid-octopus’) virus is alleged to have been the work of twenty-seven year-old Masato Nakatsuji from Osaka prefecture who is also, not coincidentally, serving a suspended sentence for creating a similar icon replacement program in 2008.

Victims reported having the normal file icons on their PCs replaced with apparently home-made drawings of squid, octopuses and sea urchins. The files themselves became inaccessible, which might conceivably have been an unintended outcome of the infection.

"I wanted to see how much my computer programming skills had improved since the last time I was arrested," Nakatsuji is reported to have told Tokyo police.

One victim is said to have 11,000 out of 64,000 files on his PC destroyed before he realised that he had a virus. All told, it is believed that between 20,000 and 50,000 PCs in Japan might have been infected with the virus, distributed using a disguised file buried in the Winny file-sharing system.