Koutetsu Sangokushi, Code Geass: Hangyaku no Lelouch R2 Recommendations
In Code Geass, the protagonist Lelouch is basically a lot like Koumei in Koutetsu Sangokushi. However the difference is in the characters and tactical analysis--Code Geass's is...deeper. In Koutetsu Sangokushi the characters are bound by the power of the Sovereign/Imperial Seal, wanting to keep it in their possession, but in Code Geass, the "power/supernatural" thing is the geass--a power that differs with each person.
Of course I don't want to give anything away so therefore I won't say any more. But a recommendation is to watch the first code geass before the second or else you'll be confused in some parts.