Momoko is from the Japanese 桃子 — momo (peach) + ko (child). Momoko is one of the Japanese feminine names — particularly popular in the post-WWII era (Showa + Heisei). Hello! Project J-pop figure.
Momoko does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Momoko reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.