“Gigantic / Big / Large / Great” in Japanese is 巨, read kyo (きょ). It is a Jōyō kanji taught in Japanese secondary school (junior & senior high) — the 高手 · Master tier beyond the grade 1–6 Kyōiku set, and appears in words such as 巨大 (huge, gigantic).
What does 巨 mean?
Same sound, different character — the classic trap. Compare them side by side: