Keiko sits next to 3 phonetic neighbors — Kiko, Keko, and Reiko are the closest matches by sound. Most share Keiko's Japanese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"joyful child"
"law, rule, model conduct"
"gratitude, love"
"twin"
"moonlight, night beauty"
"fictional warrior queen"
"syllabic script, graceful"
"hand ball, embroidered sphere"
"sunny, radiant warmth"
"self-arising"
"now go"
Similar sound: These names share phonetic patterns with Keiko — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Japanese origins, giving them the same cultural heritage as Keiko.
Rhythm: Keiko is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.