diff --git a/th04/main/boss/reset.cpp b/th04/main/boss/reset.cpp
index d06568e1..a386af43 100644
--- a/th04/main/boss/reset.cpp
+++ b/th04/main/boss/reset.cpp
@@ -7,7 +7,7 @@ void near boss_reset(void)
 #if GAME == 5
 	boss_custombullets_render = nullfunc_near;
 #endif
-	boss.phase = 0;
+	boss.phase = PHASE_BOSS_HP_FILL;
 	boss.mode = 0;
 	boss.mode_change = 0;
 	boss.phase_frame = 0;
diff --git a/th04/main/phase.hpp b/th04/main/phase.hpp
index deaff2ec..dc2e2088 100644
--- a/th04/main/phase.hpp
+++ b/th04/main/phase.hpp
@@ -1,4 +1,6 @@
-// Midboss and boss phases
+// Common midboss and boss phases
+static const unsigned char PHASE_BOSS_HP_FILL = 0;
+static const unsigned char PHASE_BOSS_ENTRANCE_BB = 1;
 #if (GAME == 5)
 	static const unsigned char PHASE_BOSS_EXPLODE_SMALL = 253;
 	static const unsigned char PHASE_BOSS_EXPLODE_BIG = 254;
diff --git a/th04/main/phase.inc b/th04/main/phase.inc
index f7770b24..6f166dde 100644
--- a/th04/main/phase.inc
+++ b/th04/main/phase.inc
@@ -1,3 +1,5 @@
+PHASE_BOSS_HP_FILL = 0
+PHASE_BOSS_ENTRANCE_BB = 1
 if (GAME eq 5)
 	PHASE_BOSS_EXPLODE_SMALL = 253
 	PHASE_BOSS_EXPLODE_BIG = 254
diff --git a/th04_main.asm b/th04_main.asm
index f55b7526..84af8015 100644
--- a/th04_main.asm
+++ b/th04_main.asm
@@ -5054,7 +5054,7 @@ var_2		= word ptr -2
 ; ---------------------------------------------------------------------------
 
 loc_E8D8:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		ja	short loc_E91D
 		mov	ax, _boss_pos.cur.x
 		sar	ax, 4
@@ -5426,7 +5426,7 @@ stage5_render	proc near
 
 		enter	2, 0
 		push	si
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jb	short loc_EC01
 		cmp	_boss_phase, PHASE_EXPLODE_BIG
 		jb	short loc_EC56
@@ -9184,7 +9184,7 @@ var_2		= word ptr -2
 		add	dx, 146
 		mov	[bp+var_2], dx
 		call	super_put pascal, si, di, dx
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	loc_11961
 		cmp	_boss_phase_frame, 128
 		jle	loc_11961
@@ -9381,7 +9381,7 @@ var_2		= word ptr -2
 		add	dx, ax
 		mov	[bp+var_2], dx
 		call	super_put pascal, si, di, dx
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	loc_11A90
 		cmp	_boss_phase_frame, 192
 		jl	loc_11A90
@@ -10212,7 +10212,7 @@ include th04/main/boss/backdrop.asm
 @orange_bg_render$qv	proc near
 		push	bp
 		mov	bp, sp
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_12199
 		cmp	_boss_phase_frame, 192
 		jge	short loc_121E1
@@ -10222,7 +10222,7 @@ include th04/main/boss/backdrop.asm
 ; ---------------------------------------------------------------------------
 
 loc_12199:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_121BF
 		call	@boss_backdrop_render$qiic pascal, (32 shl 16) or 136, 1
 		mov	ax, _bb_boss_seg
@@ -10270,9 +10270,9 @@ loc_121E6:
 @kurumi_bg_render$qv	proc near
 		push	bp
 		mov	bp, sp
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jz	short loc_1223D
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_1221B
 		call	@boss_backdrop_render$qiic pascal, (32 shl 16) or 96, 0
 		mov	ax, _bb_boss_seg
@@ -10340,7 +10340,7 @@ sub_12247	endp
 @elly_bg_render$qv	proc near
 		push	bp
 		mov	bp, sp
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		ja	short loc_12285
 		cmp	_boss_phase_frame, 2
 		jle	short loc_122CD
@@ -10399,7 +10399,7 @@ loc_122D2:
 @@entrance_cel		= byte ptr -1
 
 		enter	2, 0
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_122EB
 		cmp	_boss_phase_frame, 2
 		jg	short loc_1235F
@@ -10407,7 +10407,7 @@ loc_122D2:
 ; ---------------------------------------------------------------------------
 
 loc_122EB:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_12338
 		mov	ax, _boss_phase_frame
 		mov	bx, 8
@@ -10474,7 +10474,7 @@ loc_1235F:
 @@entrance_cel		= byte ptr -1
 
 		enter	2, 0
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_12378
 		cmp	_boss_phase_frame, 2
 		jg	short loc_123EC
@@ -10482,7 +10482,7 @@ loc_1235F:
 ; ---------------------------------------------------------------------------
 
 loc_12378:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_123C5
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -11160,7 +11160,7 @@ table_1289F	dw loc_12484
 		push	si
 		push	di
 		call	_grcg_setmode_tdw
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_12921
 		mov	ah, GC_RGI
 		call	_grcg_setcolor_direct_seg1_raw
@@ -11196,7 +11196,7 @@ loc_12904:
 ; ---------------------------------------------------------------------------
 
 loc_12921:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_12958
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -11256,7 +11256,7 @@ public @MUGETSU_GENGETSU_BG_RENDER$QV
 @@entrance_cel		= byte ptr -1
 
 		enter	2, 0
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_12996
 		cmp	_boss_phase_frame, 2
 		jg	short loc_12A05
@@ -11269,7 +11269,7 @@ loc_12991:
 ; ---------------------------------------------------------------------------
 
 loc_12996:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_129E3
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -27824,7 +27824,7 @@ public @boss_reset$qv
 		mov	bp, sp
 		setfarfp	_boss_update, nullfunc_far
 		mov	_boss_fg_render, offset nullfunc_near
-		mov	_boss_phase, 0
+		mov	_boss_phase, PHASE_BOSS_HP_FILL
 		mov	_boss_mode, 0
 		mov	_boss_mode_change, 0
 		mov	_boss_phase_frame, 0
diff --git a/th05/main/boss/render.cpp b/th05/main/boss/render.cpp
index 1e0e2c4a..4dfa633d 100644
--- a/th05/main/boss/render.cpp
+++ b/th05/main/boss/render.cpp
@@ -524,9 +524,9 @@ void near shinki_bg_type_d_update(void)
 
 void pascal near shinki_bg_render(void)
 {
-	if(boss.phase == 0) {
+	if(boss.phase == PHASE_BOSS_HP_FILL) {
 		boss_backdrop_render(PLAYFIELD_LEFT, SHINKI_STAGE_BACKDROP_TOP, 1);
-	} else if(boss.phase == 1) {
+	} else if(boss.phase == PHASE_BOSS_ENTRANCE_BB) {
 		unsigned char entrance_cel = (boss.phase_frame / 4);
 		if(entrance_cel < TILES_BB_CELS) {
 			boss_backdrop_render(PLAYFIELD_LEFT, SHINKI_STAGE_BACKDROP_TOP, 1);
@@ -657,9 +657,9 @@ void near exalice_hexagrams_update_and_render(void)
 
 void pascal near exalice_bg_render(void)
 {
-	if(boss.phase == 0) {
+	if(boss.phase == PHASE_BOSS_HP_FILL) {
 		tiles_render_after_custom_bg(boss.phase_frame);
-	} else if(boss.phase == 1) {
+	} else if(boss.phase == PHASE_BOSS_ENTRANCE_BB) {
 		unsigned char entrance_cel = (boss.phase_frame / 4);
 		boss_bg_fill_col_0();
 		tiles_bb_col = 15;
diff --git a/th05/main014.cpp b/th05/main014.cpp
index 5082e012..534b1d09 100644
--- a/th05/main014.cpp
+++ b/th05/main014.cpp
@@ -15,6 +15,7 @@
 extern "C" {
 #include "th03/formats/cdg.h"
 #include "th04/math/motion.hpp"
+#include "th04/main/phase.hpp"
 #include "th04/main/playfld.hpp"
 #include "th04/main/null.hpp"
 #include "th04/main/score.hpp"
diff --git a/th05_main.asm b/th05_main.asm
index f47fc02d..7f0fe898 100644
--- a/th05_main.asm
+++ b/th05_main.asm
@@ -1733,7 +1733,7 @@ sub_C52D	proc near
 		idiv	bx
 		or	dx, dx
 		jnz	short loc_C565
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jz	short loc_C555
 		mov	al, _bomb_frame
 		mov	ah, 0
@@ -2819,7 +2819,7 @@ public @SARA_BG_RENDER$QV
 @sara_bg_render$qv	proc near
 		push	bp
 		mov	bp, sp
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_D09F
 		cmp	_boss_phase_frame, 2
 		jg	short loc_D0EF
@@ -2827,7 +2827,7 @@ public @SARA_BG_RENDER$QV
 ; ---------------------------------------------------------------------------
 
 loc_D09F:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_D0C8
 		call	@boss_backdrop_render$qiic pascal, (64 shl 16) or 16, 0
 		mov	ax, _bb_boss_seg
@@ -2879,7 +2879,7 @@ public @LOUISE_BG_RENDER$QV
 		push	bp
 		mov	bp, sp
 		push	si
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_D108
 		cmp	_boss_phase_frame, 2
 		jg	short loc_D17A
@@ -2887,7 +2887,7 @@ public @LOUISE_BG_RENDER$QV
 ; ---------------------------------------------------------------------------
 
 loc_D108:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_D153
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -2953,7 +2953,7 @@ public @ALICE_BG_RENDER$QV
 		push	bp
 		mov	bp, sp
 		push	si
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_D194
 		cmp	_boss_phase_frame, 2
 		jg	short loc_D206
@@ -2961,7 +2961,7 @@ public @ALICE_BG_RENDER$QV
 ; ---------------------------------------------------------------------------
 
 loc_D194:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_D1DF
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -3028,7 +3028,7 @@ public @MAI_YUKI_BG_RENDER$QV
 @@entrance_cel		= byte ptr -1
 
 		enter	2, 0
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_D220
 		cmp	_boss_phase_frame, 2
 		jg	short loc_D299
@@ -3036,7 +3036,7 @@ public @MAI_YUKI_BG_RENDER$QV
 ; ---------------------------------------------------------------------------
 
 loc_D220:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_D272
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -3105,9 +3105,9 @@ public @YUMEKO_BG_RENDER$QV
 @@entrance_cel		= byte ptr -1
 
 		enter	2, 0
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jz	short loc_D31D
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_D2FB
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -6440,7 +6440,7 @@ var_6		= word ptr -6
 ; ---------------------------------------------------------------------------
 
 loc_11001:
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jnz	short loc_11029
 		mov	ax, _boss2_pos.x
 		sar	ax, 4
@@ -6798,13 +6798,13 @@ var_2		= word ptr -2
 		enter	4, 0
 		push	si
 		push	di
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jbe	short loc_113B9
 		cmp	_boss_phase, PHASE_BOSS_EXPLODE_BIG
 		jb	loc_1162C
 
 loc_113B9:
-		cmp	_boss_phase, 1
+		cmp	_boss_phase, PHASE_BOSS_ENTRANCE_BB
 		jnz	short loc_113C9
 		cmp	_boss_phase_frame, 32
 		jge	loc_1162C
@@ -7481,7 +7481,7 @@ loc_12083:
 loc_12092:
 		cmp	_dream, 2
 		jbe	short loc_120B1
-		cmp	_boss_phase, 0
+		cmp	_boss_phase, PHASE_BOSS_HP_FILL
 		jz	short loc_120A7
 		cmp	_stage_frame_mod2, 0
 		jz	short loc_120B6
@@ -15994,7 +15994,7 @@ loc_1AF66:
 loc_1AF85:
 		call	@dialog_animate$qv
 		mov	_overlay1, offset @overlay_boss_bgm_update_and_rend$qv
-		mov	_boss_phase, 0
+		mov	_boss_phase, PHASE_BOSS_HP_FILL
 		mov	_boss_phase_frame, 0
 		mov	_boss_fg_render, offset sub_10F12
 		mov	_boss_hp, 7900