九つ
ここのつ · kokonotsu · JLPT N5 · noun
nine (things)
9️⃣ 九つ = kokono (native nine) + つ (counter for things)
つ is the native Japanese general counter, as in 一つ hitotsu, 二つ futatsu. Kokono is the old native word for nine, also heard in 九日 kokonoka (ninth day). So kokonotsu literally reads nine + things.
九 — single stroke; bent hook form
九 originally pictured a bent arm or elbow, drawn as a curved hooked line. It was borrowed phonetically to write the number 'nine' because the words sounded alike, and that numeric meaning eventually replaced the original.