This is the 8360th most frequent Japanese word.
徹也
"徹也" is a Japanese male given name meaning "thorough" or "dedicated."
Here, 徹也 functions as a proper noun referring to a person's name "Tetsuya."
徹也は今日の会議に参加しました。
Tetsuya attended today's meeting.
In this sentence, 徹也 is used as the subject and agent in an action, reflecting the ownership and the activity being performed by a person named "Tetsuya."
徹也が決定した方針は、会社にとって重要です。
The policy decided by Tetsuya is important for the company.
Here, 徹也 is used to denote possession, associating the opinions with the person named "Tetsuya."