diff --git a/th01/main/boss/b10j.cpp b/th01/main/boss/b10j.cpp
index 6b175cd9..383bed6c 100644
--- a/th01/main/boss/b10j.cpp
+++ b/th01/main/boss/b10j.cpp
@@ -8,6 +8,7 @@ extern "C" {
 #include "planar.h"
 #include "th01/v_colors.hpp"
 #include "th01/math/area.hpp"
+#include "th01/hardware/egc.h"
 #include "th01/hardware/palette.h"
 #include "th01/formats/pf.hpp"
 #include "th01/formats/ptn.hpp"
@@ -57,6 +58,32 @@ static inline void ent_free(void) {
 }
 // --------
 
+// Only called while Mima isn't visible anyway. But even apart from that, it
+// barely would have any effect anywhere, as the Mima sprite is blitted to both
+// VRAM pages. This *might* have been supposed to crossfade between various
+// cels? …Nah, why would you do that by blitting whole lines.
+void mima_vertical_sprite_transition_broken(void)
+{
+	if((boss_phase_frame < 10) || ((boss_phase_frame % 4) != 0)) {
+		return;
+	}
+	pixel_t half_h = ((boss_phase_frame - 10) * 2);
+	if(half_h >= (MIMA_H / 2)) {
+		boss_phase_frame = 0;
+		return;
+	}
+	// And besides, *VRAM width*?! This is completely broken.
+	egc_copy_rect_1_to_0_16(
+		ent_still.cur_left, (ent_still.cur_top + half_h), ent_still.vram_w, 8
+	);
+	egc_copy_rect_1_to_0_16(
+		ent_still.cur_left,
+		(ent_still.cur_top + (MIMA_H - 8) - half_h),
+		ent_still.vram_w,
+		8
+	);
+}
+
 void mima_setup(void)
 {
 	boss_palette_snap();
diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index 9ecd3b9f..6f83dce9 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -10834,57 +10834,7 @@ loc_1E735:
 		retf
 sub_1E659	endp
 
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_1E739	proc far
-		push	bp
-		mov	bp, sp
-		push	si
-		cmp	_boss_phase_frame, 10
-		jl	short loc_1E798
-		mov	ax, _boss_phase_frame
-		mov	bx, 4
-		cwd
-		idiv	bx
-		or	dx, dx
-		jnz	short loc_1E798
-		mov	ax, _boss_phase_frame
-		add	ax, -10
-		add	ax, ax
-		mov	si, ax
-		cmp	si, 80
-		jl	short loc_1E768
-		mov	_boss_phase_frame, 0
-		jmp	short loc_1E798
-; ---------------------------------------------------------------------------
-
-loc_1E768:
-		push	8
-		push	mima_still.BE_vram_w
-		mov	ax, mima_still.BE_cur_top
-		add	ax, si
-		push	ax
-		push	mima_still.BE_cur_left
-		call	_egc_copy_rect_1_to_0_16
-		push	8
-		push	mima_still.BE_vram_w
-		mov	ax, mima_still.BE_cur_top
-		add	ax, 152
-		sub	ax, si
-		push	ax
-		push	mima_still.BE_cur_left
-		call	_egc_copy_rect_1_to_0_16
-		add	sp, 10h
-
-loc_1E798:
-		pop	si
-		pop	bp
-		retf
-sub_1E739	endp
-
+	extern @mima_vertical_sprite_transition_$qv:proc
 	extern @mima_setup$qv:proc
 	extern @mima_free$qv:proc
 	extern @mima_select_for_rank$qmiiiii:proc
@@ -11747,7 +11697,7 @@ loc_1EFE5:
 		cmp	byte_39E25, 0
 		jnz	short loc_1EFF8
 		mov	mima_still.BE_hitbox_orb_inactive, 1
-		call	sub_1E739
+		call	@mima_vertical_sprite_transition_$qv
 		jmp	short loc_1F051
 ; ---------------------------------------------------------------------------