The Devil is a Part-timer vol 4 (2016) by Satoshi Wagahara & Akio Hiiragi. Emi finds out who Suzono really is, and there is a new fast food shop competing with Maou's. Finished 13th June 2016, second read.
The Devil is a Part-timer! vol 2 (2015) by Satoshi Wagahara & Akio Hiiragi. Lucifer and Olba turn up, causing disasters. Maou does dialogue criticism, and Albert and Eme arrive and are confused. Finished 3rd June 2016, third read.