The character nin (or shinobi) is made up of two japanese kanji. The top part to (pronounced "toh") means "blade." The lower part shin (pronounced "sheen") means "heart" or "spirit." Together they mean "stealth, endurance, or perseverance." A more poetic translation could be, "Although the enemy holds his blade menacingly above my heart, in the end I will endure and eventually prevail."