Shimanchu MiRiKa

Based on a series of Chiikawa comics posted on X by Nagano from March to November 2023, known as the "Siren Arc" . One day, while Chiikawa and Hachiware were relaxing in the square, Usagi suddenly appeared with a flyer stuck to its face. When Hachiware checked the flyer, it was an invitation reading “Special Invitation to a Special Island.” Lured by promises like “Get 100x rewards for simple island quests!” and “Limited-edition island ramen, exclusive sweets—sweet and spicy treats all practically free!”, Chiikawa and the others decided to go on the island retreat. Boarding the ship alongside Rakko, who was suspicious of the flyer's contents, the group landed on the island... only to find something waiting for them there...!?

"Mini Ika-Musume" side-story episodes.

Around the the 37th year of the Meiji Era (1904) in the midst of the Russo-Japanese war, the small Japanese army, in need of assistance, uses its special flying (thanks to a benevolent demon) ship, the Amanohara, to attack Russia's major base at Port Arthur (Lushun). Umakai Shintaro, a Russian diplomat originally from Japan, defects and goes to Sapporo to teach at a girls academy. However, that girls academy is not typical - it is on board the Amanohara, and the five girls Shintaro teaches are known as the Raimu Unit - girls with the ability to summon powerful beings to fight for them. Shintaro eventually becomes their teacher and general in battle, and so the six embark on a weird and excessively erotic journey, as Shintaro helps the girls overcome their weaknesses, become stronger for the final stand at Lushun, and also understand the motives of the "Russian Spiritual Corps" that assist the opponent, which, unfortunately, has one member whom Shintaro knew well...

One day, Mukoujima Takurou, a boy in high school who loves fishing, catches a pig tailed mermaid called Muromi-san who speaks in the Hakata dialect. She comes to visit Takurou often, along with her fellow mermaids Sumida-san, Fuji-san, Levia-san, Hii-chan, and even some other fantastical creatures such as Yeti and Harpy!