Princess Aiko, the only child of Crown Prince Naruhito and his wife, Princess Masako, attended the entrance ceremony Sunday at Gakushuin Girls' Junior High School.
"I am looking forward (to starting a new school life)," the 12-year-old told reporters after taking photos with her parents in front of the gate to the campus in Shinjuku Ward, Tokyo.
"We hope she will have a fruitful school life," the couple said in a statement.
Roughly 200 new students have joined the school. About 60 — including Aiko — graduated last month from Gakushuin Elementary School, a private school traditionally attended by the royals.