When was the video for 'Rainbow Island Letter with Diamond Edition' released?

It was released on YouTube on May 12, 2026.

What makes this series so captivating for children?

The series captivates children because all six main characters appear in every volume, with the perspective changing in each volume, deepening the connections between the characters as the story progresses. Additionally, each volume includes a real 'letter' from the main character, creating an experiential feature.

Which specific volume was experienced in this monitor video?

Volume 4, 'The Secret Gift,' was experienced in this monitor video.

What is the setting and theme of the story?

The story is set in a full-board magical academy called 'Unicorn Academy' on 'Rainbow Island.' It deals with themes such as friendship, misunderstandings, confidence, and individuality, which are common issues faced by elementary school students.

Can you tell me about the history of the 'Letter with' series?

The 'Letter with' series started in 2014 and, as of 2026, has celebrated its 12th anniversary.

'Read It All at Once!' - YouTube Video Released for 'Rainbow Island with Letters: Diamond Edition'

Published May 25, 2026 9:00 PM ・ Updated Jun 14, 2026 4:14 AM ・ 4 min read ・ Source: PR TIMES

Gakken Co., Ltd. has released a YouTube video featuring parent-child monitors for the children's book 'Rainbow Island with Letters: Diamond Edition.' The video showcases how the series' layered storytelling with six protagonists and physical gimmicks like actual letters foster children's continuous motivation to read.

Gakken Co., Ltd., a group company of Gakken Holdings Co., Ltd., released an introductory video for 'Rainbow Island with Letters: Diamond Edition' on YouTube on May 12, 2026. The video captures the genuine reactions of parent-child monitors to showcase the unique appeal of the series.

With comments like 'I read it all at once!' and 'I'm curious about the other characters' stories!', the series has proven to be highly engaging. In the monitor project conducted in autumn 2025, children who read Volume 4, 'Secret Present,' immediately expressed a desire to read more. A key reason for this is the series structure, where all six main characters appear throughout all volumes. By switching perspectives in each book, the same daily events are seen in a new light. This makes it easy to start from any volume, with the connections between characters deepening as the reader progresses.

Set in 'Unicorn Academy,' a magical boarding school on 'Rainbow Island,' the story follows students as they bond with their unicorn partners and navigate friendship, misunderstandings, anxiety, and courage. It incorporates themes such as 'social distance with friends' and 'finding one's true self'—topics that resonate deeply with elementary school children. Parents have also praised the series, noting that it provides hints for navigating social interactions.

Furthermore, the series includes interactive elements such as personality check pages to compare readers with characters, actual 'letters' from the protagonists, and letter sets for replies. These features provide an immersive experience, making readers feel as if they have stepped into the story's world.

While each volume is a standalone story, 'Rainbow Island with Letters: Diamond Edition' naturally encourages a continuous reading habit. As the latest series in the 'With Letters' brand, which celebrates its 12th anniversary since starting in 2014, it continues to bring excitement to children everywhere.

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Source: PR TIMES
Category: キャンペーン

'Read It All at Once!' - YouTube Video Released for 'Rainbow Island with Letters: Diamond Edition'

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