Last names for Sora, Riku, Kairi, and other kids?

[YTDN]

Sora Kyuusho (Key)
Riku Kurai (Dark)
Kairi Hime (Princess)

Sora Awai (Light)
Riku Hitteki (Rival)
Kairi Kokoro (Heart)

Sora Shunketsu (Hero)
Riku Kataki (Enemy)
Kairi Aijou (Love)

Just some random ideas with a Japanese- English online dictionary.

I also tried ones for Roxas, Namine and Organization XIII

Roxas Hangaku (Half)
Namine Kinen (Memory)
Xemnas Shuhan (Leader)
Xigbar Kuuhaku (Space)
Xaldin Uindo (Wind)
Vexen Aisu (Ice)
Lexaus Yochi (Earth)
Zexion Omoi (Mind)
Saix Shichiyou (Moon)
Axel Kasai (Fire)
Demyx Gogyou (Water)
Luxord Jikoku (Time)
Marluxia Kusabana (Flower)
Larxene Raikou (Lightning)

These ones are inspired by the element/power they control.

Roxas Kobushi (Samurai)
Namine Majo (Witch)
Xemnas Mahoutsukai (Sorcerer)
Xigbar Sogekihei (Sniper)
Xaldin Morinaito (Lance Knight)
Vexen Kagakusha (Scientist)
Lexaus Gunjin (Soldier)
Zexion Boushin (Schemer)
Saix Mikon (Wild)
Axel Shikaku (Assassin)
Demyx Odoriko (Dancer)
Luxord Bakuto (Gambler)
Marluxia Miyabita (Graceful)
Larxene Senjo (Nymph)

This is their job/title/nobody they control.

Roxas Tsuinchoushi (Twin Key)
Namine Sasshi (Brush)
Xemnas Guntou (Saber)
Xigbar Teppou (Gun)
Xaldin Yari (Spear)
Vexen Toku (Shield)
Lexaus Kanadzuchi (Hammer)
Zexion Seishin (Mind)
Saix Kasuiyaiba (Spike Sword)
Axel Hishoukiwa (Flying Edge)
Demyx Benzaiten (Music)
Luxord Karuto (Card)
Marluxia Bouken (Pole Blade)
Larxene Tsume (Claw)

And this is inspired by their weapons.