at about 4:38 pm on april 9, 2012, aono suffered a bout of post-operative multiple cerebral infarctions and was found dead. voice actress eiko hisamura announced aono's death via her twitter feed, and video game designer hideo kojima stated via his twitter that he will retire the roy campbell character from the metal gear series out of respect for aono. aono was 75 years old at the time of his death.