She reported reading forty manga magazines per month as a child, including Weekly Shōnen Jump, Ribon, Nakayoshi, and Hana to Yume.
In her final year of high school she submitted an original manga work to a contest held by Nakayoshi, and won the Silver Award.
[1] While working as an artist's assistant to Mayumi Yoshida [ja], Kubo was approached by editors at Mimi to write a three-part limited series for the magazine.
[1] Mimi folded in 1997 and Kubo transferred to its sister publication Kiss, but she struggled to write the romance stories that were typical of the magazine.
A former editor at Mimi who moved to Weekly Shōnen Jump invited Kubo to create a manga series for the magazine.