親友

1. Origins, structure, and basic meaning

• Structure: 親友 (しんゆう) is a compound noun for a very close and deeply trusted friend.
• Basic usage: 親友が相談に乗る makes the close friend the person offering advice, while 小学校からの親友だ predicates a friendship continuing since elementary school.

2. Common pitfalls and similar expressions

• Supportive person and relationship duration
  • 親友が marks the agent of support, while 小学校からの親友 uses から to mark when the relationship began. The word does not include every long-known acquaintance.