Spoiler
Near Chapter 11's end, Takuru attacks Serika with a swarm of clones of his DI-Sword. In the Visual Novel, it's explained that Serika "changes the form" of her DI-SWORD to try and block the incoming attacks, but it never actually shows this.
I thought it was just a one-off remark since this is the only time it comes up, but it's actually drawn here in the art book.
I think it's really cool, and a shame that there wasn't even a sprite or CG showing it like this. You'd never even know Serika's sword has the same eye that Takuru's has. It's like her secret origin was crystallized into her DI-SWORD itself. Thought it was worth sharing!
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