Enishi no Ito

The theme song to Dan Dan is "Enishi no Ito" (縁の糸), meaning "the (red) thread (of fate) that connects us." It comes from an ancient Chinese proverb:

An invisible red thread connects those who are destined to meet, regardless of time, place, or circumstance. The thread may stretch or tangle, but it will never break.

It is sung by Mariya Takeuchi.