Kiku (菊) is the Japanese word for "chrysanthemum" — the imperial flower of Japan, depicted on the throne of the Emperor (the Chrysanthemum Throne) and the Japanese passport.
Kiku is widely used in Japan.
Kiku 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 Kiku reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.