Doi (surname)
Doi (土井、土居、土肥) are three Japanese family names that are pronounced identically, with the first kanji of each pair of characters meaning "earth." Since they are the same phonetically, they are romanized identically: "do" for the first character and "i" for the second. Their identical pronunciation makes them function as the same surname in languages with writing systems that do not use some form of Chinese characters (for example, the Latin alphabet).
People
Hiroaki Doi, hammer thrower
Isami Doi, (1903–1965), American artist
Kathryn Doi Todd, American judge and mother of Mia Doi Todd
Koji Doi, Japanese mathematician, who introduced Doi–Naganuma lifting
Mia Doi Todd, American musician and daughter of Kathryn Doi Todd
Melissa Doi, American businesswoman and September 11 attack victim
Misaki Doi, Japanese professional tennis player
Naruki Doi, Japanese professional wrestler
Ryuichi Doi, Japanese politician
Takako Doi, Japanese female politician
Takao Doi, Japanese astronaut
Takeo Doi, (1920–2009), Japanese psychoanalyst