If you’re curious, the top 20 surnames in Japan from this site:

• Sato
• Suzuki
• Takahashi
• Tanaka
• Ito
• Watanabe
• Yamamoto
• Nakamura
• Kato
• Yoshida
• Yamada
• Sasaki
• Yamaguchi
• Matsumoto
• Inoue
• Kimura
• Hayashi
• Saito
• Shimizu

These make up roughly 18.6 million people or about 15.3% of Japan’s population. If you know a Japanese person chances are they have one of these last names, though right now there a wide variety of others, and some last names more concentrated by regions.