一筋

1. Origins, structure, and basic meaning

• Structure: 一筋, read ひとすじ, means one narrow strand or single-minded devotion to one pursuit.
• Basic usage: It can be a beam of light through clouds or a life dedicated to confectionery for decades.

2. Common pitfalls and similar expressions

• A single beam and single-minded devotion
  • It can mean one beam of light through clouds or a life devoted single-mindedly to one craft over many years.