Disclaimer: I do not own Black Clover, or any of its associated characters and lore. That right belongs to Yūki Tabata.
Having left Hage Village for the Magic Knight Entrance Exam and then heading out into the wild in a mix of dismay and frustration after being passed over, Asta had found himself at the Underwater Temple, a city filled with exceptionally strong and dense mana populated by sea god worshippers and located under the sea south of the Clover Kingdom itself, where he trained himself in his swordplay and Anti-Magic against the magic used by two of the Temple priests, Kiato and his sister Kahono. After some time, he was able to get over his initial rejection from the Magic Knight Squad Captains, and intended to prove himself again in the future, one way or another.
Taking a rest from a day of training, Asta hung out with Kahono on the nearby surface beach in the light of a full moon. In the time since the former first came to the Underwater Temple, he had bonded well with Kahono over their dreams, even though Asta hadn't quite understood yet why she blushed on occasion around him.
"Looks like a good night, huh, Asta?" Kahono asked him with a smile as they laid on the sand and gazed at the moon.
"Sure does!" Asta shouted with excitement before he began to yawn. "But the whole thing is making me sleepy for whatever reason."
Kahono giggled at his actions before taking another glance at the moon. After some thinking, she decided to continue the conversation. "Hey, Asta?" Although she was quick to pout upon seeing him already sleeping. Ultimately shrugging nonchalantly, Kahono then moved herself closer to Asta before placing a kiss on his lips. "Goodnight."
I was inspired by Drenix Warriorknight's review for The Anti-Eagle on FFN to write this, except I kept in Asta's Hage Village background for the sake of convenience. Emphasis on "inspired" because the idea was shared in a review rather than requested in a Pat-reon sort of thing, just so you all know.