Sayonara Sankaku

Today, I would like to share with you “Sayonara Sankaku” (Good-bye triangle) a picture book that introduces you to a fun world of colors and shapes. This picture book draws out children’s interest in the various shapes that abound in our daily lives through a simple but touching play on words. It is a book that nurtures children’s imagination and at the same time teaches them the joy of making new discoveries in their daily lives.

¥990 (2024/03/31 00:21時点 | Amazon調べ)

Basic Information

  • Title: Sayonara Sankaku
  • Author: Hisashi Mori, Yoshimi Wada
  • Illustrator: Ken Wakayama
  • Year of Publication: 1977
  • Publisher: Kogumasha
  • Age Range: Toddlers and up


This picture book features a very simple yet memorable story. The story begins with a play on words, “Good-bye, triangle, come again, square”. As you read the story, you will discover how many shapes, such as triangles and squares, are around you.


The most unique feature of this picture book is that it is based on the subject of shapes. With each turn of the page, various shapes, such as triangles and squares, are introduced to show how they are used in our daily lives in a fun way. And the simple yet heartwarming illustrations make the story even more appealing.

Discover and Learn

This picture book will help children deepen their awareness of shapes. They will discover the joy of discovering how various shapes are used in everyday life, which they tend to overlook. In addition, through the various shapes introduced in the picture book, children will be able to develop their creativity and powers of observation.

Recommended Readers

This picture book is recommended for children of all ages, from toddlers who are just beginning to develop an interest in shapes to elementary school students who are interested in a more complex way of looking at things. Through shapes, it will give them a chance to see the world around them with new eyes.


The book “Good-bye, triangle, come again, square” is a picture book that offers new discoveries to children through the familiar theme of shapes. The simple yet profound message of this book can be enjoyed not only by children, but also by the adults who read it to them. Why not share the joy of seeing and discovering shapes with the whole family?


I am a mother of one child with a love of picture books! The time I spend reading picture books with my child is a treasure for me. In this blog, I introduce picture books that have left a deep impression on me and share the charm of stories that nurture children's imagination and sensitivity, and also inspire us adults to learn and be moved by them. I aim to create a place where readers can connect and empathize with each other through picture books. Thank you!

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