A man, Tomohiro Iwazaki, 27, was arrested after witnesses said he attacked Tomita with a knife during an event at around 5 pm on Saturday in Koganei, Western Tokyo. The suspect admitted attacking her, reported Kyodo.
Tomita, 20, was attacked for apparently refusing a gift from the man. She was stabbed in the neck, chest and back and was found unconscious. Her condition is said to be still critical.
According to the Metropolitan Police Department, Tomita had told them earlier this month that a man named Iwazaki had been persistently sending her messages via her blog and Twitter account.
In May 2014, girl group AKB48 were attacked by a man wielding a saw at one of the group's meet-and-greet events.