Sugimoto is by far the least interesting character, really. He takes a hail of bullets to the torso in broad daylight and just shrugs it off with the "I'm plotshielded" punchline. It's obvious that he won't die until the very end, so the action doesn't really carry any weight or danger. No reason to worry about him at all, he'll just keep going. All other characters are interesting because they're under the constant looming threat of being killed, or at least heavily wounded and being taken out of the story for a long time, but Sugimoto just feels like he's there to force the plot forward with godmode. It's jarring, considering the author puts a lot of emphasis on characters dying or getting incapacitated.