The Demon's Light spell that Tatsuya was executing them with didn't really give off the feeling that they were getting killed.
At first I thought it was some magic dispelling ability since his first few victims were the body guards (who behaved like a bunch of soul-less machines), it felt like they were some kind of shikigami who got its core body destroyed. When his shots started hitting the clan members, I thought he was teleporting them into the custody of his comrades rather than killing them.
And yes, that insert song + ball scene felt like it was emulating a certain scene from FF8. Not that the song was particularly bad or anything.