Kurenai is from the Japanese kurenai (紅 — crimson, deep red). Kurenai Yuhi is a character in Masashi Kishimoto's Naruto and Naruto: Shippuden manga and anime. She is the Genjutsu mistress (illusion specialist) of Konohagakure — widely considered the leading Genjutsu user of her generation alongside Itachi Uchiha. Her Demonic Illusion: Tree Binding Death (Magen: Jubaku Satsu) and Demonic Illusion: Hell Viewing Technique are signature Genjutsu of the Naruto universe.
Kurenai 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 Kurenai reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.