今朝

1. Origins, structure, and basic meaning

• Structure: 今朝 (けさ) is a temporal noun and adverb for the morning of the day of speaking.
• Basic usage: 今朝は早く目が覚めた makes this morning the topic, while 今朝届いた手紙 adverbially locates a letter’s arrival within a relative clause.

2. Common pitfalls and similar expressions

• Temporal topic and event time
  • 今朝は contrasts one part of today, whereas 今朝届いた narrows the arrival time. The word means neither last evening nor a future morning.