Kamen Rider Ex-Aid Mighty Novel X was released on June 27, 2018. Less than one week after the release, the light novel has sold out of most stores. The publisher has announced plans to reprint the popular light novel as soon as popular.
小説 仮面ライダーエグゼイド 〜マイティノベルX〜 が大好評につき、重版決定！ 🌸🎮🌸🎮🌸
— テレビマガジン (@tele_maga) July 2, 2018
After most Kamen Rider series end, a light novel is released months later. Novelizations began with Kamen Rider Kuuga. Kamen Rider Ex-Aid is the latest series to be published in novelized form and titled Kamen Rider Ex-Aid Mighty Novel X. The Kamen Rider Ex-Aid light novel is a continuation of the series after Another Ending. This is a new story that was not told in the tv series or movies.
Yuya Takahashi (高橋悠也), who was the head writer of the series, wrote the novel. There is also a statement from Hiroki Iijima, who portrayed the main hero Emu Hojo/Kamen Rider Ex-Aid.
Article Sources: Tele-Maga Twitter