Cut the crap with the HiruMamo romance, really. I mean, I don't mind people pairing them up, I don't. I'm not a hater, I myself had been drawing couples that actually make no sense but they look good together and such. What I mean is cut talking about their romance they had in series 'cuz you know what? THERE WASN'T SUCH A THING!!
Seriously, talking about how he cared for her and trusted her's making me sick 'cuz it doesn't mean anything. He had to trust her, she was team's manager after all. He cared for her no more than for any other Devil Bat and to be honest, we all know he cared most for Musashi and Kurita so I'm sorry to break your bubble.
Another thing you can say's that they were working out well and were a great team. Well, of course they were! Hiruma's smart, Mamori's smart so they had this one in common. They both fell for american football and they had to work together. Show me a team manager that doesn't get along with team captain. You can't think of any? I wonder why's that.
One thing I agree with is that Mamori could've had a thing for Hiruma. But it was only one-sided for Christ sake! She got soft when it came to him but he had never show any interest towards her, never looked at her that way, never acted like he wants something more from her. If he did, he'd just freakin' take it, it's Hiruma! Sometimes reading all of these wishful things about them makes me wanna yell and cry. Looking at HiruMamo fans reasoning, Hiruma simply had to be obsessed with Musashi as he was coming onto him so many times when he had never come to Mamori. Not unless it was about a game they were having next. She was nothing more than a manager to him. She did have to be desperate though that she even left Sena and followed Hiruma to the Saikyoudai.
So that's it. She was just a manager who fell in one-sided love. Hiruma had never shown any interest in her. The End. Finito. Deal with it.