diff --git a/th01/main/boss/b10j.cpp b/th01/main/boss/b10j.cpp
index 12930b7c..56c20993 100644
--- a/th01/main/boss/b10j.cpp
+++ b/th01/main/boss/b10j.cpp
@@ -67,10 +67,12 @@ extern int invincibility_frame;
 extern bool16 invincible;
 extern bool initial_hp_rendered;
 
+// Whether meteor_put() has any effect.
 extern bool meteor_active;
 
 // Amount of frames between the individual steps of the spread-in transition
 extern uint8_t spreadin_interval;
+
 // Sprite pixels to spread in per frame, in one half of Mima's sprite
 extern uint8_t spreadin_speed;
 
@@ -172,7 +174,12 @@ void meteor_put(void)
 
 void mima_put_cast_both(void)
 {
+	// ZUN bug: Does not unblit the meteor if `true`, and C_CAST does not
+	// completely overlap any C_METEOR cel. In that case, small parts of the
+	// meteor are guaranteed to be left in VRAM until they're unblitted as a
+	// result of another sprite flying over them.
 	meteor_active = false;
+
 	ent_anim_sync_with_still_and_put_both(C_CAST);
 }
 
@@ -398,6 +405,14 @@ struct SquareState {
 	screen_x_t name##_center_x; \
 	screen_y_t name##_center_y;
 
+#define SquareLocal2(name) \
+	screen_x_t name##_corners_ccw_x[SQUARE_POINTS]; \
+	screen_y_t name##_corners_ccw_y[SQUARE_POINTS]; \
+	screen_x_t name##_corners_cw_x[SQUARE_POINTS]; \
+	screen_y_t name##_corners_cw_y[SQUARE_POINTS]; \
+	screen_x_t name##_center_x; \
+	screen_y_t name##_center_y;
+
 #define square_center_set(sql) { \
 	sql##_center_x = ent_still.cur_center_x(); \
 	sql##_center_y = ent_still.cur_center_y(); \
@@ -563,3 +578,74 @@ void pattern_aimed_missiles_from_square_corners(void)
 	#undef target_left
 	#undef sq
 }
+
+void pattern_static_pellets_from_corners_of_two_squares(void)
+{
+	#define sq	pattern2_sq
+
+	extern SquareState sq;
+	SquareLocal2(sql);
+
+	if(boss_phase_frame == 50) {
+		mima_put_cast_both();
+	}
+	if(boss_phase_frame < 100) {
+		return;
+	}
+	if(boss_phase_frame == 100) {
+		sq.init();
+		select_subpixel_for_rank(pattern_state.speed, 4.0f, 4.5f, 5.0f, 5.5f);
+		mdrv2_se_play(8);
+	}
+	if((boss_phase_frame % SQUARE_INTERVAL) == 0) {
+		square_center_set(sql);
+		square_corners_set(sql, sql_corners_ccw, sq.radius, sq.angle);
+		square_corners_set(sql, sql_corners_cw, sq.radius, (0x00 - sq.angle));
+		square_unput(sql_corners_ccw);
+		square_unput(sql_corners_cw);
+
+		sq.angle -= 0x06;
+		Pellets.spawn_with_cloud = true;
+
+		if(sq.radius < SEAL_CIRCUMSQUARE_RADIUS) {
+			sq.radius += SQUARE_RADIUS_STEP;
+		} else {
+			// Same corner coordinate quirk as seen in the first pattern.
+
+			for(int i = 0; i < SQUARE_POINTS; i++) {
+				unsigned char angle;
+				fire_static_from_corner(
+					angle,
+					sql,
+					sql_corners_ccw_x[i],
+					sql_corners_ccw_y[i],
+					pattern_state.speed
+				);
+				fire_static_from_corner(
+					angle,
+					sql,
+					sql_corners_cw_x[i],
+					sql_corners_cw_y[i],
+					pattern_state.speed
+				);
+				mdrv2_se_play(7);
+			}
+		}
+		square_corners_set(sql, sql_corners_ccw, sq.radius, sq.angle);
+		square_corners_set(sql, sql_corners_cw, sq.radius, (0x00 - sq.angle));
+		square_put(sql_corners_ccw);
+		square_put(sql_corners_cw);
+		Pellets.spawn_with_cloud = false;
+	}
+	if(boss_phase_frame > 320) {
+		square_center_set(sql); // Not redundant!
+		square_corners_set(sql, sql_corners_ccw, sq.radius, sq.angle);
+		square_corners_set(sql, sql_corners_cw, sq.radius, (0x00 - sq.angle));
+		square_unput(sql_corners_ccw);
+		square_unput(sql_corners_cw);
+		boss_phase_frame = 0;
+		meteor_activate();
+	}
+
+	#undef sq
+}
diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index ca39393e..1aff4a8a 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -8783,298 +8783,11 @@ mima_still	equ <boss_entity_0>
 		corners_x:dword, corners_y:dword, center_x:word, center_y:word, radius:word, angle:byte, points:word
 	extern @pattern_aimed_then_static_pellet$qv:proc
 	extern @pattern_aimed_missiles_from_squa$qv:proc
+	extern @pattern_static_pellets_from_corn$qv:proc
 main_29_TEXT	ends
 
 main_29__TEXT	segment	byte public 'CODE' use16
 
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_1ECF0	proc far
-
-@@angle		= byte ptr -23h
-@@sq_center_y		= word ptr -22h
-@@corners_y_2		= byte ptr -20h
-@@corners_x_2		= byte ptr -18h
-@@corners_y_1		= byte ptr -10h
-@@corners_x_1		= byte ptr -8
-
-		enter	24h, 0
-		push	si
-		push	di
-		cmp	_boss_phase_frame, 50
-		jnz	short loc_1ED01
-		call	@mima_put_cast_both$qv
-
-loc_1ED01:
-		cmp	_boss_phase_frame, 100
-		jl	loc_1EF81
-		cmp	_boss_phase_frame, 100
-		jnz	short loc_1ED3A
-		mov	_pattern2_sq.S_radius, 32
-		mov	_pattern2_sq.S_angle, 0
-		call	@mima_select_for_rank$qmiiiii stdcall, offset _mima_pattern_state, ds, large 40h or (48h shl 16), large 50h or (58h shl 16)
-		push	8
-		call	_mdrv2_se_play
-		add	sp, 0Eh
-
-loc_1ED3A:
-		mov	ax, _boss_phase_frame
-		mov	bx, 8
-		cwd
-		idiv	bx
-		or	dx, dx
-		jnz	loc_1EF00
-		mov	ax, mima_still.BE_cur_left
-		add	ax, 64
-		mov	di, ax
-		mov	ax, mima_still.BE_cur_top
-		add	ax, 80
-		mov	[bp+@@sq_center_y], ax
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_1]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_1]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		push	word ptr _pattern2_sq.S_angle	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_2]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_2]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		mov	al, 0
-		sub	al, _pattern2_sq.S_angle	; angle
-		push	ax	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	4	; point_count
-		push	ss
-		lea	ax, [bp+@@corners_y_1]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_1]
-		push	ax
-		call	_graph_r_lineloop_unput
-		push	4	; point_count
-		push	ss
-		lea	ax, [bp+@@corners_y_2]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_2]
-		push	ax
-		call	_graph_r_lineloop_unput
-		add	sp, 14h
-		mov	al, _pattern2_sq.S_angle
-		add	al, -06h
-		mov	_pattern2_sq.S_angle, al
-		mov	_Pellets.PELLET_spawn_with_cloud, 1
-		cmp	_pattern2_sq.S_radius, 112
-		jge	short loc_1EDD4
-		add	_pattern2_sq.S_radius, 8
-		jmp	loc_1EE95
-; ---------------------------------------------------------------------------
-
-loc_1EDD4:
-		xor	si, si
-		jmp	loc_1EE8E
-; ---------------------------------------------------------------------------
-
-loc_1EDD9:
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_y_1]
-		add	bx, ax
-		mov	ax, ss:[bx]
-		sub	ax, [bp+@@sq_center_y]
-		push	ax
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_x_1]
-		add	bx, ax
-		mov	ax, ss:[bx]
-		sub	ax, di
-		push	ax
-		call	iatan2
-		mov	[bp+@@angle], al
-		pushd	0 or (0 shl 16)
-		pushd	PM_REGULAR or (0 shl 16)
-		push	_mima_pattern_state
-		push	word ptr [bp+@@angle]
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_y_1]
-		add	bx, ax
-		push	word ptr ss:[bx]
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_x_1]
-		add	bx, ax
-		push	word ptr ss:[bx]
-		push	ds
-		push	offset _Pellets
-		call	@CPellets@add_single$qiiuci15pellet_motion_tiii
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_y_2]
-		add	bx, ax
-		mov	ax, ss:[bx]
-		sub	ax, [bp+@@sq_center_y]
-		push	ax
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_x_2]
-		add	bx, ax
-		mov	ax, ss:[bx]
-		sub	ax, di
-		push	ax
-		call	iatan2
-		mov	[bp+@@angle], al
-		pushd	0 or (0 shl 16)
-		pushd	PM_REGULAR or (0 shl 16)
-		push	_mima_pattern_state
-		push	word ptr [bp+@@angle]
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_y_2]
-		add	bx, ax
-		push	word ptr ss:[bx]
-		mov	bx, si
-		add	bx, bx
-		lea	ax, [bp+@@corners_x_2]
-		add	bx, ax
-		push	word ptr ss:[bx]
-		push	ds
-		push	offset _Pellets
-		call	@CPellets@add_single$qiiuci15pellet_motion_tiii
-		push	7
-		call	_mdrv2_se_play
-		add	sp, 2Ah
-		inc	si
-
-loc_1EE8E:
-		cmp	si, 4
-		jl	loc_1EDD9
-
-loc_1EE95:
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_1]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_1]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		push	word ptr _pattern2_sq.S_angle	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_2]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_2]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		mov	al, 0
-		sub	al, _pattern2_sq.S_angle	; angle
-		push	ax	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	4 or (7 shl 16)	; (point_count) or (col shl 16)
-		push	ss
-		lea	ax, [bp+@@corners_y_1]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_1]
-		push	ax
-		call	_graph_r_lineloop_put
-		push	4 or (7 shl 16)	; (point_count) or (col shl 16)
-		push	ss
-		lea	ax, [bp+@@corners_y_2]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_2]
-		push	ax
-		call	_graph_r_lineloop_put
-		add	sp, 18h
-		mov	_Pellets.PELLET_spawn_with_cloud, 0
-
-loc_1EF00:
-		cmp	_boss_phase_frame, 320
-		jle	short loc_1EF81
-		mov	ax, mima_still.BE_cur_left
-		add	ax, 64
-		mov	di, ax
-		mov	ax, mima_still.BE_cur_top
-		add	ax, 80
-		mov	[bp+@@sq_center_y], ax
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_1]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_1]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		push	word ptr _pattern2_sq.S_angle	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	ss	; corners_x (segment)
-		lea	ax, [bp+@@corners_x_2]
-		push	ax	; corners_x (offset)
-		push	ss	; corners_y (segment)
-		lea	ax, [bp+@@corners_y_2]
-		push	ax	; corners_y (offset)
-		push	di	; center_x
-		push	[bp+@@sq_center_y]	; center_y
-		push	_pattern2_sq.S_radius	; radius
-		mov	al, 0
-		sub	al, _pattern2_sq.S_angle	; angle
-		push	ax	; angle
-		push	4	; points
-		call	@regular_polygon$qnit1iiiuci
-		push	4	; point_count
-		push	ss
-		lea	ax, [bp+@@corners_y_1]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_1]
-		push	ax
-		call	_graph_r_lineloop_unput
-		push	4	; point_count
-		push	ss
-		lea	ax, [bp+@@corners_y_2]
-		push	ax
-		push	ss
-		lea	ax, [bp+@@corners_x_2]
-		push	ax
-		call	_graph_r_lineloop_unput
-		add	sp, 14h
-		mov	_boss_phase_frame, 0
-		call	@meteor_activate$qv
-
-loc_1EF81:
-		pop	di
-		pop	si
-		leave
-		retf
-sub_1ECF0	endp
-
-
 ; =============== S U B	R O U T	I N E =======================================
 
 ; Attributes: bp-based frame
@@ -10325,7 +10038,7 @@ loc_1FB5E:
 loc_1FB6B:
 		cmp	word_39E78, 2
 		jnz	short loc_1FB78
-		call	sub_1ECF0
+		call	@pattern_static_pellets_from_corn$qv
 		jmp	short loc_1FB86
 ; ---------------------------------------------------------------------------