Boundaries and worlds with 界
界 primarily means “boundary” or “a defined area or society”.
Etymology
界 is a phono-semantic compound built from 田 (field) and 介 as the sound component, with the original sense of boundary lines dividing fields.
Human and Social Worlds
世界 (World)
世界 is the world and the people in it. It also means a particular sphere, such as the world of art.
It combines 世 (society) with 界 (world) to show the world of human society.

Alicia and Akari visit an island that’s modeled after part of Japan back on Earth. There, an elderly local woman tells the two of the fox spirits that visit the human world there. Akari is excited at the prospect of meeting one, but the old woman gives her a warning: on rare occasion, a fox will take a person back home with them.
- おばあさん:
- 「神さまの世界と人間の世界は違うやさかい」
- “Since the god world and the human world are different...”
- 「連れて行かれたらあかん」
- “...you mustn't get taken away.”
Limits and Boundaries
限界 (Limit)
限界 means the limit or boundary beyond which something cannot go.
It combines 限 (limit) with 界 (boundary) to show a boundary line.
Example 1 of 3: At one's limit with 限界

Mina wants to hurry and eat her lunch, as she’s very hungry. Yukari reminders her they still have one more class first.
- ミナ:
- 「もう限界だよ!こんなんじゃ次の授業、集中できないよー。」
- “I'm already at my limit! As things are, come next class I won't be able to concentrate.”
Example 2 of 3: Being at my limit is no good with あかん

At a special event, the expected host doesn’t show for dinner. After finishing their meals, the guests continue to wait until past midnight. As most guests decide to retire to their rooms for the night, Heiji finds himself yawning.
- 平次:
- 「あかんオレももう限界や…」
- “No good, I'm also already at my limit...”
Example 3 of 3: The limit of teamwork with 限界

On a snowy day, Alicia starts making a snowball. As it gets bigger, Akari joins in. They continue to roll the snowball until it grows too big for them to keep pushing. At that moment, a random person passing by notices their effort.
- 灯里:
- 「アリシアさん… 二人の力ではこれが限界かと」
- “Alicia... This is the limit of what we can do together.”
- 男:
- 「おおっ 大きいな」
- “Oh! That's a big one.”
視界 (Field of view)
視界 means one’s field of vision or how clearly one can see it.
It combines 視 (look) with 界 (range) to show the range of sight.

Akatsuki asks Akari for a gondola ride to his destination. Along the way, he asks whether he’ll make his deadline. Akari suggests Alicia should take over, but Akatsuki says he’s Akari’s customer (and paying the cheaper fare). Realizing her responsibility, Akari turns the gondola around so she can use her high-speed backward rowing. Alicia apologizes to Akatsuki for the turnaround.
- アリシア:
- 「今からお客様の視界を遮る漕ぎ方をさせてもらいます」
- “From now on, she'll be using a rowing technique that blocks your view.”
- 暁:
- 「むぅ?」
- “Mm?”
Other Realms
他界 (Passing away)
他界 is a respectful euphemism for a person’s death.
It combines 他 (other) with 界 (world) to show the other world.

Kogoro takes a client to the home of someone she’d be communicating with via pagers. They show the household family a music box that was left to the client by her correspondence partner. The music it plays reminds the homeowner of the koto his mother used to play.
- 小五郎:
- 「母さんってもしかしてあのお写真の…」
- “By 'Mom', could that be the one in that photo…?”
- 常雄:
- 「ええ… 父の横の写真が三年前に他界した母の春菜です…」
- “Yes... The photo beside my father's is my mother, Haruna, who passed away three years ago...”
異世界 (Other world)
異世界 means another world or dimension. In modern fiction, it usually means a fantasy world of magic and monsters.
It combines 異 (other) with 世界 (world) to show another world separate from ordinary reality.

Zen lived in a glittering, idyllic town until his family moved. During his first day of school, he found everyone to be glaring and rugged. Rather than being gentle and playful, his classmates sought a brawl and chased after him.
- 禅:
- 「ここは異世界だ」
- “This is another world.”
- 「異世界に迷い込んだに違いない」
- “I must have wandered into another world.”