The thirty-first day is my birthday.

We have our wedding on the twenty-third day of the month.

He succeeded in a difficult project with the spirit of 'ishi no ue ni mo sannen', which means great works are performed by perseverance.

He is training his triceps brachii muscle every day.

He goes to the gym every day to train his triceps surae muscle.

He damaged his peroneus tertius muscle due to a foot injury.

The Tokyo metropolitan region is the center of Japan's economy.

Mr. Shimooka is my best friend.

This shape is called a gyrobifastigium.

This shape is called a gyrobifastigium.