The final collection of Unico manga has been released in Japan as of today, December 3! Similar to the other books, two sizes are available to choose from. This book is the First Grader version of comics which have Esuo, Ragon, Unico, and Chao having silly adventures.

B5 format: 176 × 250 mm / 6.9 × 9.8 in
B6 format: 125 × 176 mm / 4.9 × 6.9 in

You can find both versions on honto's website here:
(On Demand Book) Unico Shougaku Ichinensei Version - B5 Size
(On Demand Book) Unico Shougaku Ichinensei Version - B6 Size