The rarest Japanese last name is "Saitou," with only 0.77% of the population having this surname, according to a survey by Meiji Yasuda Life Insurance Company in 2019. The name originates from two kanji characters meaning "purification" or "worship" and "wisteria" and has a long history of prominent figures in literature, music, and martial arts. Other rare Japanese last names include Kawabata, Izumi, Ogawa, Nakamura, and Abe. The rarity of some surnames may be due to geographical factors or historical events like wars or natural disasters that caused many people with certain last names to perish. Preserving rare last names is crucial for maintaining Japan's cultural heritage.