TOKYO — A woman was held hostage for 18 hours by a knife-wielding man at the headquarters of a transportation company in Shimane Prefecture, western Japan, before being released unharmed on Wednesday, local police said.

After the standoff involving an employee in her 40s being forcibly confined for 18 hours, Nakao was arrested by police for alleged criminal confinement

Kaisei Nakao, 23, who entered the premises of Ueda Cold Corp. in Izumo City a day earlier at around 2:20 pm local time wielding a bladed instrument, told staff he wanted to see the firm's president and went on to barricade himself inside the premises.

After the standoff involving an employee in her 40s being forcibly confined for 18 hours, Nakao was arrested by police for alleged criminal confinement, police said.

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Ueda Cold Corp., located in a quiet neighborhood comprised mainly of rice fields and storage units, employs 170 people and is involved in delivering cold, perishable items, sources with knowledge of the matter said.

The hostage was confined in a conference room and watched throughout the protracted ordeal, although local reports said the woman was not restrained in any way, and Nakao and his victim were not thought to be acquainted.

During the standoff with the police, Nakao told the police he had a "personal grudge against someone" related to the business, although it is not thought to be the firm's president or the woman whom he took hostage, police said.

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The hostage-taker, who hails from Chiba Prefecture in eastern Japan, did not make any monetary or other demands, said police.