Okay, so I guess with all these triangles San in Sanko's name supposed to mean or at least sound like 3, his name in katakana. And Shi in Shimada obviously death but also homonym for 4. And Damemaru's is literally Hajime, meaning first, with kanji for 1. And together with Avakian they're all Four Evils, supposedly. Though I don't see anything resembling 2 in Avakian's name.
I rarely read comments so I probably not the first who noticed that name pattern but still wanted to share with people who didn't notice yet, like me.