Translation

島国根性の / 視野の狭い / 閉鎖的な

Meaning

Narrow-minded or unwilling to accept ideas or people from outside one's own group or region.

Examples

• The company's insular culture made it difficult for new employees to suggest innovative changes.
  The company's insular culture made it difficult for new employees to suggest innovative changes.
• He grew up in an insular community where outsiders were rarely seen or welcomed.
  He grew up in an insular community where outsiders were rarely seen or welcomed.