周日圈

• 冂(surround; border)RADICAL
• 土(earth; soil; ground)ASSOCIATIVE
• 口(mouth; door)ASSOCIATIVE

A territory surrounded by boundaries like earth and gates enclosed all around.

• 日(sun (pictograph))ASSOCIATIVE

The character 日 is drawn as a round sun with light rays inside.

• 囗(surround; square)RADICAL
• 卷(roll; book)PHONETIC

A circle is a closed boundary that wraps around, like a rolled paper forming a complete loop.