English wiki:
Japanese funeral - Wikipedia
Japanese wiki article:
葬儀 - Wikipedia
The only mention of a katana is in the Japanese article, which briefly mentions a ナステァ窶堙ィ窶慊 mamori-gatana; a ceremonial knife that is placed on the chest before the body is cremated. According to the article, the reflective blade helps the deceased to cut down or ward off demons and their minions. I showed the article to my Japanese friend, and she had never heard of this custom. Funeral rites vary from place to place, and family to family. I do not believe the mamori-gatana is buried with the remains. I am not sure what hiroyuki meant by his post. :?