Ayako Kaetsu reports to work at a nursery school in Hiratsuka, Kanagawa Prefecture, on Dec. 3, 2020. (Yoichiro Kodera)

YOKOHAMA--A nursery school teacher was arrested for the alleged assault of a 1-year-old girl she was looking after that resulted in the child’s death in 2017, according to police.

Kanagawa prefectural police announced on Nov. 1 the arrest of Ayako Kaetsu, 45, who worked at the Nakahara nursery school in Hiratsuka, Kanagawa Prefecture, on suspicion of inflicting injury resulting in death.

Kaetsu, who lives in Isehara in the prefecture, has reportedly denied the allegation.

She is suspected of having assaulted Ayaka Yanagida, a Hiratsuka toddler who attended the certified private nursery school.

The assault is believed to have occurred between around 12:35 p.m. and 1:05 p.m. on April 27, 2017, in a room at the school that the children used for taking naps, according to investigators.

Ayaka suffered traumatic subarachnoid bleeding resulting from a bruised head and fractured skull and was pronounced dead at around 3:05 p.m. at the hospital that she had been rushed to.

The suspect began working as a teacher at the nursery school in October 2010. Ayaka’s parents had asked the nursery school to improve how Kaetsu cared for their child before the incident, according to investigative sources.

The alleged assault came to light after the suspect informed the school's director that Ayaka was unconscious, and the director made an emergency call on the same day of the incident.

“A 1-year-old girl looks sick,” the director told the person who answered the call.

Based on security camera footage of the nursery school and accounts of other staff members, investigators determined that Kaetsu was not only looking after Ayaka but other children as well by herself right before the director made the emergency call.

Police said they decided to arrest Kaetsu because based on opinions from doctors, they believe Ayaka likely died from a strong blow to her head and have ruled out the injury resulted from a fall.

The nursery school had 19 staff members, including teachers, and 124 children aged between 0 to 5 attending at the time of the incident, according to data obtained through an information disclosure request to Hiratsuka.

The nursery school interviewed Kaetsu and other staff members following Ayaka's death, but did not find any problems with their conduct, according to a lawyer for the school.

The suspect reportedly quit the nursery school at the end of March.

(This article was written by Shinjiro Omiya, Kyoko Doi and Rikuri Kuroda.)