It is a zabuton designed for a gift in celebration of someone’s 88th birthday, which usually comes in yellow or gold. The kanji ‘米(bei)’ can be separated to into the three kanjis, ‘八十八(hachiju-hachi=88)’, so the celebration of the age of 88 is called ‘beiju.’
Although the celebration of beiju is said to be the time-honored custom since the Muromachi era, some say that beiju was originally the celebration of the age of 80. The honoree is supposed to wear yellow garments such as sleeveless vest like the kanreki celebration.