The regular form of a Japanese adjective always ends with -い. Such adjectives already have the functionality of the だ copula built into them, meaning they naturally denote the core subject as possessing the attribute.1

Tip

In order to more easily visualise the function built into い adjectives, imagine the English version of the adjective with an β€œis” preceding it.

Examples

  • あかい β†’ is red
  • 倧きい β†’ is big

Example: Tomato is red

γƒˆγƒžγƒˆγŒγ‚γ‹γ„

Image source: Yuru Yuri Nachuyachumi!

Info

あかい (red) is the adjective, and the primary subject γƒˆγƒžγƒˆ(tomato) is linked to it.

Footnotes

  1. Japanese from Scratch (1) ↩