diff --git a/th01/main/boss/b15j.cpp b/th01/main/boss/b15j.cpp
index 2a56bdc7..2ea2ec9d 100644
--- a/th01/main/boss/b15j.cpp
+++ b/th01/main/boss/b15j.cpp
@@ -159,6 +159,13 @@ inline void kikuri_ptn_free(void) {
 // Patterns
 // --------
 
+enum kikuri_phase_4_subphase_t {
+	P4_SOUL_ACTIVATION = 0,
+	P4_PATTERN = 1,
+
+	_kikuri_phase_4_subphase_t_FORCE_INT16 = 0x7FFF
+};
+
 #define pattern_state	kikuri_pattern_state
 extern union {
 	int interval;
@@ -201,6 +208,8 @@ void kikuri_setup(void)
 	hud_hp_first_white = PHASE_2_END_HP;
 	hud_hp_first_redwhite = PHASE_5_END_HP;
 
+	// Redundant – already called before the sprites are first rendered, and
+	// (0, 0) isn't used to indicate "soul is not alive".
 	souls[0].pos_set(0, 0, 50,
 		SOUL_AREA_LEFT, SOUL_AREA_RIGHT, SOUL_AREA_TOP, SOUL_AREA_BOTTOM
 	);
@@ -549,3 +558,28 @@ void near pattern_spinning_aimed_rings(void)
 		);
 	}
 }
+
+kikuri_phase_4_subphase_t near phase_4_souls_activate(void)
+{
+	if(boss_phase_frame == 200) {
+		souls[0].pos_set(
+			(LIGHTBALL_CENTER_X - (SOUL_W / 2)),
+			(LIGHTBALL_CENTER_Y - (SOUL_H / 2)), 50,
+			SOUL_AREA_LEFT, SOUL_AREA_RIGHT, SOUL_AREA_TOP, SOUL_AREA_BOTTOM
+		);
+		souls[1].pos_set(
+			(LIGHTBALL_CENTER_X - (SOUL_W / 2)),
+			(LIGHTBALL_CENTER_Y - (SOUL_H / 2)), 50,
+			SOUL_AREA_LEFT, SOUL_AREA_RIGHT, SOUL_AREA_TOP, SOUL_AREA_BOTTOM
+		);
+	} else if((boss_phase_frame > 200) && ((boss_phase_frame % 2) == 0)) {
+		soul_move_and_render(0, -4, -3);
+		soul_move_and_render(1, +4, -3);
+		if(souls[0].cur_top < (
+			SOUL_AREA_TOP + playfield_fraction_y(2 / 21.0f)
+		)) {
+			return P4_PATTERN;
+		}
+	}
+	return P4_SOUL_ACTIVATION;
+}
diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index fb3cff60..a000e9b7 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -14715,6 +14715,7 @@ main_34_TEXT	segment	byte public 'CODE' use16
 		y:word, mask:word
 	@pattern_symmetric_spiral_from_di$qv procdesc near
 	@pattern_spinning_aimed_rings$qv procdesc near
+	@phase_4_souls_activate$qv procdesc near
 main_34_TEXT	ends
 
 main_34__TEXT	segment	byte public 'CODE' use16
@@ -14722,50 +14723,6 @@ main_34__TEXT	segment	byte public 'CODE' use16
 		;org 4
 		assume es:nothing, ss:nothing, ds:_DATA, fs:nothing, gs:nothing
 
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_23F16	proc near
-		push	bp
-		mov	bp, sp
-		cmp	_boss_phase_frame, 200
-		jnz	short loc_23F62
-		call	@CBossEntity@pos_set$qiiiiiii stdcall, offset kikuri_soul_0, ds, 304, large 208 or (50 shl 16), large 32 or (576 shl 16), large 64 or (400 shl 16)
-		call	@CBossEntity@pos_set$qiiiiiii stdcall, offset kikuri_soul_1, ds, 304, large 208 or (50 shl 16), large 32 or (576 shl 16), large 64 or (400 shl 16)
-		add	sp, 24h
-		jmp	short loc_23F99
-; ---------------------------------------------------------------------------
-
-loc_23F62:
-		cmp	_boss_phase_frame, 200
-		jle	short loc_23F99
-		mov	ax, _boss_phase_frame
-		mov	bx, 2
-		cwd
-		idiv	bx
-		or	dx, dx
-		jnz	short loc_23F99
-		push	large (0 shl 16) or (-4 and 0FFFFh)
-		push	-3
-		call	@soul_move_and_render$qiii
-		push	large (1 shl 16) or (+4 and 0FFFFh)
-		push	-3
-		call	@soul_move_and_render$qiii
-		cmp	kikuri_soul_0.BE_cur_top, 96
-		jge	short loc_23F99
-		mov	ax, 1
-		pop	bp
-		retn
-; ---------------------------------------------------------------------------
-
-loc_23F99:
-		xor	ax, ax
-		pop	bp
-		retn
-sub_23F16	endp
-
-
 ; =============== S U B	R O U T	I N E =======================================
 
 ; Attributes: bp-based frame
@@ -15991,7 +15948,7 @@ loc_24C07:
 		call	@pattern_spinning_aimed_rings$qv
 		cmp	word_35D14, 0
 		jnz	short loc_24C27
-		call	sub_23F16
+		call	@phase_4_souls_activate$qv
 		jmp	short loc_24C2A
 ; ---------------------------------------------------------------------------