"When I thought about children in Ukraine, I remembered my experience as a child during the war and I thought I should write more about what was like," Kuroyanagi said at a news conference on Tuesday.
She said one of the things children dislike about war is the lack of freedom as they are not allowed to do anything. Kuroyanagi added that it wasn't easy recalling what it was like back then, but she did her best.
Her original memoir details Kuroyanagi's life when she meets new friends and teachers after transferring to a unique elementary school in Tokyo.
The descriptions of vibrant children and a friendly teacher-student atmosphere struck a chord and the book was a record-breaking best-seller in Japan.
"Totto-chan" has been translated into more than 20 languages and sold more than 25 million copies worldwide.
The sequel, which shares the same title, shines a spotlight on Kuroyanagi's life as she flees to the northern prefecture of Aomori following the devastating US air raid on Tokyo in March 1945.
It also covers her music school graduation, her work as an actor at NHK and her studies in New York.
A hit in China
"Totto-chan" has been a hit in China, where 16.8 million copies have been sold.
The Chinese company that's been publishing it for two decades says the book's message is very popular.
"Chinese readers — like many others around the world — are attracted to teachers who care about the personality of each child and their attitude toward teaching, as shown in the book," says Li Jing Zhi, the head of the Chinese publisher's international department. "The book's messages include 'you can be yourself' and 'you don't need to be the best as long as you can enjoy your life."
The publisher says it wants to translate the sequel of "Totto-chan," which has been featured in several school textbooks, and publish it next June.
"Children who read the original have grown up and I'm sure they're interested in what happens to the little girl next," Li says.
Kuroyanagi wants kids to enjoy books
Kuroyanagi said at the news conference that writing the sequel after 42 years was a good opportunity for her to look back on her own life.
"While writing the sequel, I was most surprised to find that I haven't changed at all over the years," she said. "I believe the new book is interesting."
When asked what she expects of children today, she said she hopes they will learn to love books.
"I read so many books when I was a child because they were my only entertainment. I still read them before going to bed, and learn a lot from them," she said. "By reading 'Totto-chan' I hope children realize reading is fun."