Bungo Stray Dogs is both. It began as a light novel and then was transformed into a manga. The light novel provides detailed storytelling, while the manga brings the characters and scenes to life visually.
Well, you could say there are hints of love here and there. But it's not a conventional love story. The series is primarily known for its action and supernatural elements with love being a secondary aspect.
One of the main themes is the exploration of special abilities. Each character has their own unique ability, which leads to various power struggles and cooperation. Another theme is the concept of good and evil. The characters are not simply divided into good or bad, but are complex individuals with different motives and backstories.
Well, in the 'bungo stray dogs' series, each volume usually has a central conflict. Maybe in volume 15, it could be related to the power struggles between different groups of ability - users. It might also focus on the development of certain characters, like how they face new challenges and grow. However, without reading it, this is just speculation.