Mayumi sits next to 3 phonetic neighbors — Mayu, Naomi, and Yumi are the closest matches by sound. Most share Mayumi's Japanese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"true bow (archery)"
"bright, torch (via Helena/Jelena)"
"Finnish feminine name, possibly related to air or era"
"shadow, shade"
"enlightenment, sudden awakening"
"America-inspired"
"sunflower direction (poetic)"
"tranquility, stability"
"courage, bravery (勇気)"
"Shinto deity of rice, foxes, and prosperity"
"crimson beauty (alternate kanji)"
Similar sound: These names share phonetic patterns with Mayumi — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Japanese origins, giving them the same cultural heritage as Mayumi.
Rhythm: Mayumi is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.