Kaiseisha releases two new baby books, "Wanwann" and "Buu-buu," as the new Tanoshii Otoehon series

Kaiseisha Co., Ltd. (publisher, headquarters: Shinjuku City, Tokyo; President and CEO: Yuji Imamura) announced that it simultaneously released two new baby picture books in the series titled "Tanoshii Otoehon" on Saturday, May 9, 2026: "Wanwann" and "Buu-buu," both written and illustrated by Hiroyuki Arai.

Book details:
Wanwann: https://www.kaiseisha.co.jp/books/9784031033008
Buu-buu: https://www.kaiseisha.co.jp/books/9784031033107

Aiming to create a new standard in baby picture books, Hiroyuki Arai, who became a long-seller with his book Rei-zouko (over 180,000 copies sold), released these two titles while also marking his 20th anniversary as a picture-book creator this year. He asked a basic question: what is the most enjoyable picture book an infant can listen to again and again?

The defining feature of this series is that it is a picture book that helps babies enjoy the sounds that become the foundation of language. When the book is opened, objects familiar to babies appear together with related onomatopoeic expressions.

In "Wanwann," only unvoiced onomatopoeia are used, such as "kutsu pattapatta" and "tsumiki konkōn."
In "Buu-buu," only voiced onomatopoeia are used, such as "densha gotoŋ gotoŋ" and "zō dosun dosun."

Each page changes its background color vividly, while the clear illustrations attract attention and the pleasant onomatopoeia please the ears. It is a picture book that can be enjoyed repeatedly with babies, and is recommended as a first book for new parents.

You can also read the author interview here: https://kaiseiweb.kaiseisha.co.jp/t/ath/ath2605/

Author profile
Hiroyuki Arai (あらい・ひろゆき), born in Tokyo in 1974, is a picture-book author, designer, and part-time lecturer at Tokyo Zokei University. He has created many titles including: "Reizouko," "Toire," "Ofuro," "Notte Iru no wa Dare?" "Onamae Oshiete," "Oyasumi Nasai," "Obake to Hotcake," "Iroiro Baa," "Chuuchu Tako-kaina," and "Kokoro o Nakushita Kaijuu."

Book specifications
Title: Wanwan (Tanoshii Otoehon)
Author / Illustrator: Hiroyuki Arai
Price: 990 JPY (tax included)
Size: 14 cm x 14 cm (board book)
Target age: 0+ years
Pages: 16
ISBN: 978-4-03-103300-8
Publication date: May 9, 2026
Official bibliographic details (Kaiseisha): https://www.kaiseisha.co.jp/books/9784031033008

Title: Buu-buu (Tanoshii Otoehon)
Author / Illustrator: Hiroyuki Arai
Price: 990 JPY (tax included)
Size: 14 cm x 14 cm (board book)
Target age: 0+ years
Pages: 16
ISBN: 978-4-03-103310-7
Publication date: May 9, 2026
Official bibliographic details (Kaiseisha): https://www.kaiseisha.co.jp/books/9784031033107