The diehard otaku Kirino Kousaka has returned and settled back into life in Japan with her friends and family. Despite what her older brother Kyousuke has previously done for her, Kirino continues to give him the cold shoulder, much to his frustration. He is worried that his persuasion for Kirino to drop her track and field training in America and return home may have severely strained his relationship with her. On top of that, Kyousuke now also has to decode a bold and cryptic message from Ruri "Kuroneko" Gokou, his junior at school as well as Kirino's friend. As the ties between the two siblings and their friends deepen, Kirino and Kyousuke will soon have to figure out how they want to deal with these relationships, helping each other realize their own feelings in the process. In spite of that, Kirino still manages to find time to satisfy her otaku needs with the company of her brother. [Written by MAL Rewrite]

Humans have been polluting the ocean for a long time, carelessly pouring their garbage and desecrating the waters that many creatures call home. The denizens of the sea have suffered at their poisoning hands. Finally, one certain squid has had enough and vows to punish the humans' selfish actions. Possessing all the fearsome abilities of a squid such as powerful hair-tentacles, the ability to spit ink, and even use bioluminescence at will, Ika Musume takes it upon herself to rise from the depths of the ocean and exact revenge upon humanity! She surfaces at a certain Lemon Beach House, a restaurant managed by the sisters Eiko and Chizuru Aizawa. Thinking them to be an easy first step toward world domination, she immediately declares war against them, only to find out that she is, quite literally, a fish out of water! To make things worse, she destroys a part of a wall of the beach house in an attempt to flaunt her squiddy superiority and is consequently forced into becoming a waitress to pay the repair costs. Beached for the time being after tasting a thorough defeat at the hands of the Aizawa sisters, Ika Musume is forced to put her plans for world domination on hold. Despite these setbacks, Ika Musume soon finds herself right at home in her unexpected position as Lemon Beach House's newest employee. Wacky and hilarious, Shinryaku! Ika Musume follows her brand new life on the surface as she makes precious memories and meet lots of new people. With her newfound acquaintances, Ika Musume is looking to take the world by storm, one squid ink spaghetti at a time! [Written by MAL Rewrite]

Recap film that will cover the match against Aobajosai High School that took place in the second season.

(Source: MAL News)

The movie is a compilation of episodes 9-13 of the 2017 television series. Riko and Reg descend to the third layer where Riko has her first experience of the Curse. They descend to the fourth layer where Riko's arm is injured by an Orbed Piercer and Reg tries to save her. Nanachi comes to their aid and saves Riko's poisoned arm. In return Nanachi asks Reg to kill her immortal companion Mitty. Nanachi then joins Riko and Reg in their quest to reach the bottom of the Abyss. (Source: Wikipedia)