Short summary: She does not participate or is mentioned.
(There is no gallery)
Short summary: This was an episode where the characters of the series are shown in comic situations when they are out of their adventures.
One of the shorts shows Meliodas and King trying to spy on Elizabeth and Diana. Meliodas walks in to bathe them and Diane is thrilled, King enters too (but with his appearance of obese adult) and Diane annoys throwing away.
Another shows how Diane and Ban are testing their brute strength: Diane uses a pinkie and Ban her full hand. But then Diane defeats Ban using her full hand.
Also in another short one makes mention to Diana like "a beautiful lady" (when it was Matrona) on the part of one of the Holy Knights.