The 'Gate SDF light novel' is about a fictional scenario where a gate appears. It could be about the military strategies of the SDF when they enter the unknown through this gate. It might also be about the characters within the SDF who have to adapt to the new environment, like dealing with magic if there is any in the new world, and their personal growth throughout the adventures.
Well, 'Gate SDF' light novel typically involves a story where there's some sort of portal or 'gate' that leads to different worlds or situations. It often features the Self - Defense Forces (SDF) in various roles. Maybe they are exploring the new world that the gate has opened, facing strange creatures, or dealing with political and cultural differences between their world and the one on the other side of the gate.