Overlord: Ple Ple Pleiades

Taking characters from otherwise more serious isekai franchises, these specials are light-hearted parodies of the original work using SD characters. 

Short specials parodying the (serious) main series with comedic skits, maybe slightly off-character characters and chibi character designs. Aired alongside the main series. 

Extra for an isekai franchise, this special parodies the main show using chibification of the characters for a hort comedy. 

Both series consist in short specials having the characters in chibi style doing silly things. However, while Akame ga Kill Theater follows independent stories, Overlord Specials has a kind of plot involving the characters.