It was time to give Yuga his quirk. On Yuga's eighth birthday, his quirk manifested.
From Williams's quirk the ability to analyze, From Momo Yaoyorozu the ability to create materials from body fat, and Eijiro Kirishima's ability to affect his body.
William met Momo in their school and Eijiro Kirishima while out sampling passing strangers' quirks. William was looking to get his hands on a certain vampire's quirk but never ran into them.
William followed the smell of blood expecting to find Hemico but instead found a shark-man eating another man in an ally. Luckily he was too busy with his meal to notice William sneaking away holding in his lunch.
Yuga's quirk lets him identify materials by touch and alter his body structure to match the material. More body fat is converted with denser materials. On release, the body structure returns to normal, and fat is restored.
Yuga's first experience with his quirk was his hand becoming the same plastic as the knife he used to cut his slice of cake. followed by him running around the house touching everything.
Author Note: Ill come back to this another time.