New Release: Mendako Ninja Returns in 'Mendako Ninja: To Ryuugu Park' – The Beloved Deep-Sea Octopus Hero Saves Peace in an Underwater Amusement Park!

The Idol of the Deep Sea: Mendako Ninja

Mendako is a deep-sea octopus relative, about 15–20 cm in size—small enough to fit in the palm of your hand. With ear-like fins that flap as it swims, its adorable appearance has earned it the nickname 'the idol of the deep sea.'

'Mendako Ninja' is a picture book born from the unique characteristics of this creature, written by author Tokuno Yumi and illustrated by Hidaka Naoto, renowned for his whimsical animals and botanical art.

Now, the long-awaited sequel, 'Mendako Ninja: To Ryuugu Park,' is here!

The hit series returns—Mendako Ninja’s second adventure!

When young Mendako child Menmen learns from the Mendako Newspaper that an amusement park called 'Ryuugu Park' is opening in the deep sea, he receives an urgent request from the Regal Fish: 'Please come quickly!'

'Welcome to Ryuugu Park!'

Before him lies an underwater paradise. But just before the grand show begins, Princess Otohime—the star of the event—is nowhere to be found. The park staff pleads with Mendako Ninja to step in and play the princess.

With the help of the Ryuugu Knight Squad, Mendako Ninja transforms into Princess Otohime!

Suddenly, the deep-sea fish Mizuuo, which eats anything in its path, attacks—putting everyone in grave danger!

Can Mendako Ninja save the peace of Ryuugu Park?

This exciting book is packed with thrilling twists and a vibrant cast of deep-sea creatures, offering endless fun for children.

Inside Pages

Inside Pages

Deep-Sea Creatures (Back Cover) ★ First-Press Bonus: 'Mendako Newspaper' with a coloring page on the reverse side!

● Book Information

Title: 'Mendako Ninja: To Ryuugu Park'

Author: Tokuno Yumi (Text)

Illustrator: Hidaka Naoto (Art)

Publisher: Iwasaki Shoten, Co., Ltd.

Price: ¥1,650 (¥1,500 + tax)

Format: A4 variant, 32 pages

Target Age: Ages 3 to early elementary school

Release Date: June 15, 2026

ISBN: 978-4-265-83258-3

Iwasaki Shoten Product Page: https://www.iwasakishoten.co.jp/book/b10168769.html

Product Video: https://www.youtube.com/shorts/A7f1QTIUH0A

● Also Available: 'Mendako Ninja' (First Book)

Title: 'Mendako Ninja'

Author: Tokuno Yumi (Text), Hidaka Naoto (Art)

Publisher: Iwasaki Shoten, Co., Ltd.

Price: ¥1,650 (¥1,500 + tax)

Format: A4 variant, 32 pages

ISBN: 978-4-265-83144-9

Iwasaki Shoten Product Page: https://www.iwasakishoten.co.jp/book/b10168769.html

Product Video: https://www.youtube.com/shorts/cNv8eO1mAm0

● Author Profiles

Tokuno Yumi

Began her career as a TV variety show scriptwriter during university. She has written scripts for NHK's 'Little Zombie Girl' musical and 'Ihatov Theatre: Midnight Star Gazing' musical. Her works include the novel 'Little Zombie Girl' (NHK Publishing) and the picture book 'Mendako Ninja' (Iwasaki Shoten). She enjoys collecting seashells and birdwatching, and lives with butterflies, stick insects, and grasshoppers.

Hidaka Naoto

Artist and illustrator based in Nara Prefecture. Graduated from the Graphic Design course at Okayama Prefectural University. Holds annual solo exhibitions while creating illustrations for magazines and advertisements. His illustrated works include 'Mendako Ninja' and children's book illustrations for 'Ghost Lee Blue' (written by Ogiyanagi Chika, both published by Iwasaki Shoten). His art primarily features imaginary animals and plants.