[SPLIT LIP]

I might suggest you wait for a sub, since there's a lot of explanation.

From what I gather, and I may be way off, the riders were orginally ancient warriors who fought with armies of full-sized monsters and other assorted horrors for land and shit using Lock Seeds to pull them from a different dimension/teleport them. Something happened and we're left uncertain of the end result. Fast forward to the future, and society is commercialised and what was once ancient and dangerous power is no common place. Lockseeds are used to settle territorial disputes (between groups sporting the Riders names, or perhaps even using their myth to be mascots) with civility by using lock seeds to summon mini-monsters to fight. However, the monsters don't look especially tame or happy about it, and one looked to... change or lash out, before of of the competitor's locks was knocked aside and it went rouge before Giam (pre-rider) closed the lock and sent it home. OR it's the exact opposite, and the Lock Seeds are used this way in the present, and the beginning is a flash forward showing what will happen with this use of mystical technology.

That's just what I've gathered from how far I'm in, but yeah. Looks like society's in for a rude awakening.

Also, the main chick is DEFFINITELY related to Hana from Den-O.

Also also, I think my guess is true, because there's bits of propaganda-style messages about the lock seeds and shit. Almost like this is a city under rule and the citizens don't know it. It's really quite interesting.