Rei sits next to 4 phonetic neighbors — Ray, Rae, and Rye are the closest matches by sound. Most share Rei's Japanese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"courtesy, respect, gratitude"
"rejoice"
"estate by the cliff"
"famous land, fame of the land"
"healer, to heal"
"God will hear"
"powerful giant, cosmic force"
"God is my illumination"
"descendant of Braonán (moisture/sorrow)"
"from Milan, middle of the plain"
"strength of God"
"peaceful town"
"living water, strength"
"descendant of Brocán (little badger)"
"precious gem, jewel"
"cultivator, earth worker"
"powerful ruler, brave power"
"tube, channel"
"gift of God's grace"
"kind, gentle, handsome"
Similar sound: These names share phonetic patterns with Rei — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Japanese kanji 礼 origins, giving them the same cultural heritage as Rei.
Rhythm: Rei is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.