It is not obvious how.

"...am I missing the power of summoning platforms, that would be grand if I were, I never tried it—"

Pew pew PEW.

"I think it's one of the generic ones? Same basic idea as the shields Yamanaka's been putting up. But you're a little nonstandard -" Pwing pwing. "If you tell me where you want 'em I can do them for now?"

"I was thinking of trying to explode the witch."

"So you want like - oh, huh, it's not happening for me either. Maybe it doesn't work in stopped time or something?"

"—oh. I guess that—no, I don't think it makes any sense, or like, I don't know why it would, you can still do your arrows and string." Can he reach the witch with a grenade from where he is?

How good's his aim for a person-sized target flying in the air a good twenty metres away from him?

...not that good.

"No idea why the arrows would be different. You wanna... tie an arrow to a grenade?"

"Not sure if we can time it right, and I'd want to warn Yamanaka-san first, and it might not even do anything."

"Did you ever buy a sword?"

"I cloned one. Three, actually."

"Will swording the witch in stopped time let it move?"

"If I can cut it, yes; if I wouldn't have been able to, no."

"...I can go try cutting off its head and if this turns out really badly you can go back to a half second ago?"

He does NOT want Haru to get hurt even if he will retroactively not have been hurt!!!!!

"Why not just let Yamanaka-san do that? She's good with a sword." And she is also not Yutaka's BOYFRIEND.

"Because she can't ditch the string on no notice if she needs more maneuvering space, but we can go up to her and suggest it, I guess."

Mrrrrrrrrr.

"I'll follow your lead, whatever you think is best."

"We should at least consult her." He starts picking his way through the maze of arrows and monsters toward where Yamanaka is mid-swing.

"Yeah. She might swing at you though if she's surprised, maybe I could unpause for half a second for the arrows and bullets to finish hitting their targets first?"

"...yeah, good thought, let's check if that works first."

"Alright, three, two, one..."

Projectiles fly. The minions are taken down—some of them still twitch brokenly on the floor, but they don't seem to share their master's ability to refold themselves into extra mass—but the arrows and bullets targetting the witch are either deflected by well-timed glass shards and deceptively resilient origami or tanked by her without leaving her much worse for wear.

"Okay, looks like this one needs melee," Haru sighs.

(Yamanaka's swing deflected a couple shards and made a creditable attempt at taking off the witch's head at the neck.)