diff --git a/src/sys/ags.cpp b/src/sys/ags.cpp
index db536c2..663ba47 100644
--- a/src/sys/ags.cpp
+++ b/src/sys/ags.cpp
@@ -402,7 +402,7 @@ void AGS::fade_in(int duration_ms)
 	update_screen();
 }
 
-void AGS::draw_screen(int sx, int sy, int width, int height)
+void AGS::invalidate_screen(int sx, int sy, int width, int height)
 {
 	SDL_Rect rect = {sx, sy, width, height};
 	SDL_Rect screen_rect = {0, 0, screen_width, screen_height};
diff --git a/src/sys/ags.h b/src/sys/ags.h
index 39ac8e0..d623440 100644
--- a/src/sys/ags.h
+++ b/src/sys/ags.h
@@ -120,8 +120,7 @@ public:
 	std::vector<uint32_t> get_screen_palette() const;
 	uint8 get_pixel(int dest, int x, int y) const { return vram[dest][y][x]; }
 	void set_pixel(int dest, int x, int y, uint8 color) { vram[dest][y][x] = color; }
-	// Marks a rectangle of the display screen for the next update_screen().
-	void draw_screen(int sx, int sy, int width, int height);
+	void invalidate_screen(int sx, int sy, int width, int height);
 
 	void fade_out(int duration_ms, bool white);
 	void fade_in(int duration_ms);
diff --git a/src/sys/ags_draw.cpp b/src/sys/ags_draw.cpp
index aeb2d4a..84c1eaf 100644
--- a/src/sys/ags_draw.cpp
+++ b/src/sys/ags_draw.cpp
@@ -115,7 +115,7 @@ void AGS::blit_cg(int dest, CG& cg, const SDL_Rect* src, int dx, int dy)
 	SDL_Rect dstrect = { dx, dy, src ? src->w : cg.width(), src ? src->h : cg.height() };
 	SDL_BlitSurface(cg.surface(), src, hBmpScreen[dest], &dstrect);
 	if (dest == 0) {
-		draw_screen(dstrect.x, dstrect.y, dstrect.w, dstrect.h);
+		invalidate_screen(dstrect.x, dstrect.y, dstrect.w, dstrect.h);
 	}
 }
 
@@ -151,7 +151,7 @@ void AGS::copy_screen(int src, int dest, int sx, int sy, int ex, int ey, int dx,
 		SDL_SetColorKey(src_surface, SDL_FALSE, 0);
 
 	if (dest == 0)
-		draw_screen(dx, dy, width, height);
+		invalidate_screen(dx, dy, width, height);
 }
 
 void AGS::gcopy(int gsc, int gde, int glx, int gly, int gsw)
@@ -169,7 +169,7 @@ void AGS::gcopy(int gsc, int gde, int glx, int gly, int gsw)
 	SDL_BlitSurface(hBmpScreen[src], &srcrect, hBmpScreen[dest], &destrect);
 
 	if(dest == 0) {
-		draw_screen(dx, dy, glx * 8, gly);
+		invalidate_screen(dx, dy, glx * 8, gly);
 	}
 }
 
@@ -213,7 +213,7 @@ void AGS::paint(int x, int y, uint8 color)
 		miny = std::min(y, miny);
 		maxy = std::max(y, maxy);
 	}
-	draw_screen(minx, miny, maxx - minx + 1, maxy - miny + 1);
+	invalidate_screen(minx, miny, maxx - minx + 1, maxy - miny + 1);
 }
 
 void AGS::draw_box(int index)
@@ -243,7 +243,7 @@ void AGS::draw_mesh(int sx, int sy, int width, int height)
 			vram[0][y + 1][x] = 255;
 		}
 	}
-	draw_screen(sx, sy, width, height);
+	invalidate_screen(sx, sy, width, height);
 }
 
 void AGS::box_fill(int dest, int sx, int sy, int ex, int ey, uint8 color)
@@ -251,7 +251,7 @@ void AGS::box_fill(int dest, int sx, int sy, int ex, int ey, uint8 color)
 	SDL_Rect rect = {sx, sy, ex - sx + 1, ey - sy + 1};
 	SDL_FillRect(hBmpScreen[dest], &rect, color);
 	if(dest == 0) {
-		draw_screen(sx, sy, ex - sx + 1, ey - sy + 1);
+		invalidate_screen(sx, sy, ex - sx + 1, ey - sy + 1);
 	}
 }
 
@@ -267,7 +267,7 @@ void AGS::box_line(int dest, int sx, int sy, int ex, int ey, uint8 color)
 	SDL_FillRect(hBmpScreen[dest], &left, color);
 	SDL_FillRect(hBmpScreen[dest], &right, color);
 	if(dest == 0) {
-		draw_screen(sx, sy, ex - sx + 1, ey - sy + 1);
+		invalidate_screen(sx, sy, ex - sx + 1, ey - sy + 1);
 	}
 }
 
diff --git a/src/sys/ags_text.cpp b/src/sys/ags_text.cpp
index 0fe87a0..30927da 100644
--- a/src/sys/ags_text.cpp
+++ b/src/sys/ags_text.cpp
@@ -409,7 +409,7 @@ void AGS::draw_text(std::string_view string, bool text_wait)
 		if (!draw_menu && text_wait && code != ' ') {
 			// 画面更新
 			if(screen == 0)
-				draw_screen(ctx.pos.x, dest_y, dest_x - ctx.pos.x, ascent - descent);
+				invalidate_screen(ctx.pos.x, dest_y, dest_x - ctx.pos.x, ascent - descent);
 			ctx.pos.x = dest_x;
 			// Wait
 			g_nact->text_wait();
@@ -418,7 +418,7 @@ void AGS::draw_text(std::string_view string, bool text_wait)
 	if (!draw_menu && !text_wait) {
 		// 画面更新
 		if(screen == 0)
-			draw_screen(ctx.pos.x, dest_y, dest_x - ctx.pos.x, ascent - descent);
+			invalidate_screen(ctx.pos.x, dest_y, dest_x - ctx.pos.x, ascent - descent);
 	}
 	ctx.pos.x = dest_x;
 }
diff --git a/src/sys/ags_window.cpp b/src/sys/ags_window.cpp
index eddd63c..a84fc85 100644
--- a/src/sys/ags_window.cpp
+++ b/src/sys/ags_window.cpp
@@ -156,7 +156,7 @@ void AGS::draw_push(int index)
 	int x = w.ex - 16;
 	int y = w.ey - 16;
 	draw_gaiji(0, x, y, push_bitmap ? push_bitmap : builtin_bitmap, 16, text.font_color);
-	draw_screen(x, y, 16, 16);
+	invalidate_screen(x, y, 16, 16);
 }
 
 void AGS::open_text_window(int index, bool erase)
@@ -197,7 +197,7 @@ void AGS::open_text_window(int index, bool erase)
 		SDL_SetSurfacePalette(hBmpScreen[0], w.window.palette());
 		SDL_Rect rect = {sx, sy, width, height};
 		SDL_BlitSurface(w.window.surface(), NULL, hBmpScreen[0], &rect);
-		draw_screen(sx, sy, width, height);
+		invalidate_screen(sx, sy, width, height);
 		SDL_SetSurfacePalette(hBmpScreen[0], screen_palette);
 	}
 
@@ -233,7 +233,7 @@ void AGS::close_text_window(int index, bool update)
 		SDL_SetSurfacePalette(hBmpScreen[0], w.screen.palette());
 		SDL_Rect rect = {sx, sy, width, height};
 		SDL_BlitSurface(w.screen.surface(), NULL, hBmpScreen[0], &rect);
-		draw_screen(sx, sy, width, height);
+		invalidate_screen(sx, sy, width, height);
 		SDL_SetSurfacePalette(hBmpScreen[0], screen_palette);
 	}
 
@@ -280,7 +280,7 @@ void AGS::open_menu_window(int index)
 	SDL_Rect dst_rect = {sx, sy, width, height};
 	SDL_BlitSurface(hBmpScreen[2], &src_rect, hBmpScreen[0], &dst_rect);
 	box_line(0, sx, sy, ex, sy + menu.font_size + 3, menu.frame_color);
-	draw_screen(wsx, wsy, wwidth, wheight);
+	invalidate_screen(wsx, wsy, wwidth, wheight);
 }
 
 void AGS::redraw_menu_window(int index, int selected)
@@ -297,7 +297,7 @@ void AGS::redraw_menu_window(int index, int selected)
 	SDL_Rect dst_rect = {sx, sy, width, height};
 	SDL_BlitSurface(hBmpScreen[2], &src_rect, hBmpScreen[0], &dst_rect);
 	box_line(0, sx, sy + (menu.font_size + 4) * selected, ex, sy + (menu.font_size + 4) * (selected + 1) - 1, menu.frame_color);
-	draw_screen(sx, sy, width, height);
+	invalidate_screen(sx, sy, width, height);
 }
 
 void AGS::close_menu_window(int index)
@@ -308,7 +308,7 @@ void AGS::close_menu_window(int index)
 		SDL_SetSurfacePalette(hBmpScreen[0], w.screen.palette());
 		SDL_Rect rect = {w.screen.x, w.screen.y, w.screen.width(), w.screen.height()};
 		SDL_BlitSurface(w.screen.surface(), NULL, hBmpScreen[0], &rect);
-		draw_screen(w.screen.x, w.screen.y, w.screen.width(), w.screen.height());
+		invalidate_screen(w.screen.x, w.screen.y, w.screen.width(), w.screen.height());
 		SDL_SetSurfacePalette(hBmpScreen[0], screen_palette);
 	}
 }
@@ -337,5 +337,5 @@ void AGS::draw_window(int sx, int sy, int ex, int ey, bool frame, uint8 frame_co
 		SDL_FillRects(hBmpScreen[0], rects, 4, frame_color);
 		box_line(0, sx + 4, sy + 4, ex - 4, ey - 4, frame_color);
 	}
-	draw_screen(sx, sy, ex - sx + 1, ey - sy + 1);
+	invalidate_screen(sx, sy, ex - sx + 1, ey - sy + 1);
 }
diff --git a/src/sys/nact_gakuenking.cpp b/src/sys/nact_gakuenking.cpp
index dc6bb26..b04b495 100644
--- a/src/sys/nact_gakuenking.cpp
+++ b/src/sys/nact_gakuenking.cpp
@@ -1358,7 +1358,7 @@ private:
 				ags->set_pixel(0, x + col, y + row, (cursor.body[row] & bit) ? 15 : 0);
 			}
 		}
-		ags->draw_screen(x, y, MOUSE_CURSOR_SIZE, MOUSE_CURSOR_SIZE);
+		ags->invalidate_screen(x, y, MOUSE_CURSOR_SIZE, MOUSE_CURSOR_SIZE);
 	}
 
 	// --- A key wait icon --------------------------------------------------