Sora is a Japanese name written 空 — meaning "sky" or "emptiness." In Buddhist thought, the character also carries the philosophical meaning of śūnyatā, the emptiness or openness that is the nature of all phenomena.
Sora is widely used in Japan for both girls and boys. The video game series Kingdom Hearts features a protagonist named Sora. Two soft syllables, a sky's worth of meaning.
Sora reduces to four — the number of open space.