俺

1. Origins, structure, and basic meaning

• Structure: 俺 (おれ) is a first-person pronoun used chiefly by men in familiar or rough speech. 俺は marks topic; 俺も adds the speaker inclusively.
• Basic usage: In direct quotation it identifies the person leaving first; in recollection it adds that the speaker also climbed the mountain.

2. Common pitfalls and similar expressions

• Speaker in direct quotation and speaker included in an experience
  • は topicalizes the person going home; も includes the speaker among people with the experience. Its register differs from neutral, formal 私.