Farewell Yuko, Sister of the Moon (さようなら夕子よ、月の妹よ Sayōnara Yūko yo, Tsuki no Imōtoyo) is the twenty-eighth episode of Ultraman Ace.
Yuko Minami reveals through flashbacks that she is a princess from an ancient lunar civilization that had been destroyed by Yapool and one of his many Terrible-Monster, named Lunaticks. She decides to reveal this to Seiji Hokuto, and the two keep it secret. However, TAC find out that disturbingly, Lunaticks has arrived on Earth, and is intent on destroying Earth in the same way as he did to the Moon! It's up to Seiji and Yuko to combine into Ace together one more time, and take down the creature who threatens all of Earth.
- Ultraman Ace Volume 7 features episodes 25-28.