The reason I try not to be TOO overly critical of BSD is not just because it's unfinished but also just Tachihara.
Like Asagiri just introduced this funky side character once as a typical mafioso and barely did anything with him and then BOOM. Backstory, character arc, depth, etc.
Was it done perfectly? Probably not though I think the foreshadowing was there.
But like...Tachihara went from co-leader of one of the most dangerous PM hit squads with not much beyond that to government spy brought in after Ango whose motives and loyalty are torn between many factors and factions and who stepped up to be one of the connecting factors between the Hunting Dogs, PM, AND ADA. Complex and likeable and maybe unexpected but not in a bad way.
Credit where credit is due, yes.
