diff --git a/include/input.h b/include/input.h
index 3c77d8b..6899317 100644
--- a/include/input.h
+++ b/include/input.h
@@ -141,5 +141,7 @@ void handle_events(void);
 bool key_is_down(enum sact_keycode code);
 void key_clear_flag(void);
 void mouse_get_pos(int *x, int *y);
+void mouse_get_wheel(int *forward, int *back);
+void mouse_clear_wheel(void);
 
 #endif /* SYSTEM4_INPUT_H */
diff --git a/src/ffi.c b/src/ffi.c
index bd24746..7e6c9d9 100644
--- a/src/ffi.c
+++ b/src/ffi.c
@@ -141,6 +141,7 @@ extern struct static_library lib_DrawPluginManager;
 extern struct static_library lib_File;
 extern struct static_library lib_Math;
 extern struct static_library lib_MsgLogManager;
+extern struct static_library lib_MsgLogViewer;
 extern struct static_library lib_MsgSkip;
 extern struct static_library lib_OutputLog;
 extern struct static_library lib_PlayMovie;
@@ -158,6 +159,7 @@ static struct static_library *static_libraries[] = {
 	&lib_File,
 	&lib_Math,
 	&lib_MsgLogManager,
+	&lib_MsgLogViewer,
 	&lib_MsgSkip,
 	&lib_OutputLog,
 	&lib_PlayMovie,
diff --git a/src/hll/MsgLogManager.c b/src/hll/MsgLogManager.c
index a2b1d66..b2b30ee 100644
--- a/src/hll/MsgLogManager.c
+++ b/src/hll/MsgLogManager.c
@@ -14,11 +14,66 @@
  * along with this program; if not, see <http://gnu.org/licenses/>.
  */
 
+#include <stdlib.h>
+#include <string.h>
+#include "system4.h"
+#include "system4/string.h"
 #include "hll.h"
+#include "MsgLogManager.h"
+
+static size_t msg_log_size = 0;
+static size_t msg_log_i = 0;
+struct msg_log_entry *msg_log = NULL;
+
+#define LOG_MAX 2048
+
+static void msg_log_alloc(void)
+{
+	if (msg_log_i < msg_log_size)
+		return;
+	if (!msg_log_size)
+		msg_log_size = 1;
+
+	// rotate log
+	if (msg_log_i >= LOG_MAX) {
+		for (size_t i = 0; i < msg_log_i - LOG_MAX/2; i++) {
+			if (msg_log[i].data_type == MSG_LOG_STRING)
+				free_string(msg_log[i].s);
+		}
+		memcpy(msg_log, msg_log + (msg_log_i - LOG_MAX/2), sizeof(struct msg_log_entry) * LOG_MAX/2);
+		msg_log_i = LOG_MAX/2;
+		return;
+	}
+
+	msg_log = xrealloc(msg_log, sizeof(struct msg_log_entry) * msg_log_size * 2);
+	msg_log_size *= 2;
+}
+
+int MsgLogManager_Numof(void)
+{
+	return msg_log_i;
+}
+
+static void MsgLogManager_AddInt(int type, int value)
+{
+	msg_log_alloc();
+	msg_log[msg_log_i++] = (struct msg_log_entry) {
+		.data_type = MSG_LOG_INT,
+		.type = type,
+		.i = value
+	};
+}
+
+static void MsgLogManager_AddString(int type, struct string *str)
+{
+	msg_log_alloc();
+	msg_log[msg_log_i++] = (struct msg_log_entry) {
+		.data_type = MSG_LOG_STRING,
+		.type = type,
+		.s = string_ref(str)
+	};
+}
 
-HLL_WARN_UNIMPLEMENTED(0, int,  MsgLogManager, Numof, void);
-HLL_WARN_UNIMPLEMENTED( , void, MsgLogManager, AddInt, int type, int value);
-HLL_WARN_UNIMPLEMENTED( , void, MsgLogManager, AddString, int type, struct string *str);
 HLL_WARN_UNIMPLEMENTED(0, int,  MsgLogManager, GetType, int index);
 HLL_WARN_UNIMPLEMENTED(0, int,  MsgLogManager, GetInt, int index);
 HLL_WARN_UNIMPLEMENTED( , void, MsgLogManager, GetString, int index, struct string **str);
diff --git a/src/hll/MsgLogManager.h b/src/hll/MsgLogManager.h
new file mode 100644
index 0000000..c3e47ff
--- /dev/null
+++ b/src/hll/MsgLogManager.h
@@ -0,0 +1,36 @@
+/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+#ifndef SYSTEM4_MSGLOGMANAGER_H
+#define SYSTEM4_MSGLOGMANAGER_H
+
+enum msg_data_type {
+	MSG_LOG_INT,
+	MSG_LOG_STRING
+};
+
+struct msg_log_entry {
+	enum msg_data_type data_type;
+	int type;
+	union {
+		int i;
+		struct string *s;
+	};
+};
+
+struct msg_log_entry *msg_log;
+
+#endif /* SYSTEM4_MSGLOGMANAGER_H */
diff --git a/src/hll/MsgLogViewer.c b/src/hll/MsgLogViewer.c
new file mode 100644
index 0000000..5415cd5
--- /dev/null
+++ b/src/hll/MsgLogViewer.c
@@ -0,0 +1,110 @@
+/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include "vm.h"
+#include "vm/page.h"
+#include "system4/string.h"
+#include "hll.h"
+#include "MsgLogManager.h"
+
+struct log_data {
+	struct string *text;
+	int voice;
+	int separator;
+};
+
+static size_t log_viewer_size = 0;
+static size_t log_viewer_i = 0;
+static struct log_data *log_viewer = NULL;
+
+int MsgLogViewer_Numof(void)
+{
+	return log_viewer_i;
+}
+
+void MsgLogViewer_Clear(void)
+{
+	for (size_t i = 0; i < log_viewer_i; i++) {
+		free_string(log_viewer[i].text);
+	}
+	free(log_viewer);
+	log_viewer = NULL;
+	log_viewer_size = 0;
+	log_viewer_i = 0;
+}
+
+HLL_WARN_UNIMPLEMENTED( , void, MsgLogViewer, Add, struct page *log);
+
+void MsgLogViewer_Get(int index, struct page **log)
+{
+	// ???
+	if ((size_t)index >= log_viewer_i) {
+		(*log)->values[0].i = vm_string_ref(&EMPTY_STRING);
+		(*log)->values[1].i = 0;
+		(*log)->values[2].i = 0;
+		return;
+	}
+
+	(*log)->values[0].i = vm_string_ref(log_viewer[index].text);
+	(*log)->values[1].i = 0;
+	(*log)->values[2].i = 0;
+}
+
+static void log_viewer_alloc(void)
+{
+	if (log_viewer_i < log_viewer_size)
+		return;
+	if (!log_viewer_size)
+		log_viewer_size = 128;
+	log_viewer = xrealloc(log_viewer, sizeof(struct log_data) * log_viewer_size * 2);
+}
+
+static void log_viewer_push(struct string *s, int voice, int separator)
+{
+	log_viewer_alloc();
+	log_viewer[log_viewer_i++] = (struct log_data) {
+		.text = string_ref(s),
+		.voice = voice,
+		.separator = separator
+	};
+}
+
+int MsgLogManager_Numof(void);
+
+void MsgLogViewer_ConvertFromMsgLogManager(possibly_unused int msg_log_manager)
+{
+	int log_size = MsgLogManager_Numof();
+	MsgLogViewer_Clear();
+
+	for (int i = 0; i < log_size; i++) {
+		if (msg_log[i].data_type == MSG_LOG_INT) {
+			if (msg_log[i].type == 1102) {
+				log_viewer_push(&EMPTY_STRING, 0, 0);
+			}
+		}
+		if (msg_log[i].data_type == MSG_LOG_STRING) {
+			log_viewer_push(msg_log[i].s, 0, 0);
+		}
+	}
+}
+
+HLL_LIBRARY(MsgLogViewer,
+	    HLL_EXPORT(Numof, MsgLogViewer_Numof),
+	    HLL_EXPORT(Clear, MsgLogViewer_Clear),
+	    HLL_EXPORT(Add, MsgLogViewer_Add),
+	    HLL_EXPORT(Get, MsgLogViewer_Get),
+	    HLL_EXPORT(ConvertFromMsgLogManager, MsgLogViewer_ConvertFromMsgLogManager));
diff --git a/src/hll/SACT2.c b/src/hll/SACT2.c
index 73d321b..f1dac1b 100644
--- a/src/hll/SACT2.c
+++ b/src/hll/SACT2.c
@@ -62,14 +62,12 @@ int sact_Mouse_GetPos(int *x, int *y)
 
 void sact_Mouse_ClearWheel(void)
 {
-	// TODO
+	mouse_clear_wheel();
 }
 
 void sact_Mouse_GetWheel(int *forward, int *back)
 {
-	// TODO
-	*forward = 0;
-	*back    = 0;
+	mouse_get_wheel(forward, back);
 }
 
 void sact_Joypad_ClearKeyDownFlag(int n)
diff --git a/src/input.c b/src/input.c
index 6699c9a..ad9e30b 100644
--- a/src/input.c
+++ b/src/input.c
@@ -14,6 +14,7 @@
  * along with this program; if not, see <http://gnu.org/licenses/>.
  */
 
+#include <stdbool.h>
 #include <SDL.h>
 #include "system4.h"
 #include "gfx/private.h"
@@ -53,6 +54,19 @@ void mouse_get_pos(int *x, int *y)
 	SDL_GetMouseState(x, y);
 }
 
+static int wheel_dir = 0;
+
+void mouse_get_wheel(int *forward, int *back)
+{
+	*forward = wheel_dir > 0;
+	*back = wheel_dir < 0;
+}
+
+void mouse_clear_wheel(void)
+{
+	wheel_dir = 0;
+}
+
 static void key_event(SDL_KeyboardEvent *e, bool pressed)
 {
 	enum sact_keycode code = sdl_keytable[e->keysym.scancode];
@@ -106,6 +120,9 @@ void handle_events(void)
 		case SDL_MOUSEBUTTONDOWN:
 			mouse_event(&e.button);
 			break;
+		case SDL_MOUSEWHEEL:
+			wheel_dir = e.wheel.y;
+			break;
 		default:
 			break;
 		}
diff --git a/src/meson.build b/src/meson.build
index 0c2bef3..80a93ec 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -45,6 +45,7 @@ xsystem4 = ['audio.c',
             'hll/File.c',
             'hll/Math.c',
             'hll/MsgLogManager.c',
+            'hll/MsgLogViewer.c',
             'hll/MsgSkip.c',
             'hll/OutputLog.c',
             'hll/PlayMovie.c',