diff --git a/src/linux/nact_linux.cpp b/src/linux/nact_linux.cpp
index e26b2a4..b160377 100644
--- a/src/linux/nact_linux.cpp
+++ b/src/linux/nact_linux.cpp
@@ -1,8 +1,35 @@
 #include <stdio.h>
 #include "nact.h"
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+
+extern "C" {
+// ags_text.cpp
+char* sjis2utf(char* src);
+char* utf2sjis(char* src);
+}
+#endif
 
 void NACT::text_dialog()
 {
+#ifdef __EMSCRIPTEN__
+	static char buf[256];
+	char *oldstr = sjis2utf(tvar[tvar_index - 1]);
+	int ok = EM_ASM_({
+			var r = xsystem35.shell.inputString("文字列を入力してください", UTF8ToString($0), 8);
+			if (r) {
+				stringToUTF8(r, $1, $2);
+				return 1;
+			}
+			return 0;
+		}, oldstr, buf, sizeof buf);
+	free(oldstr);
+	if (ok) {
+		char *newstr = utf2sjis(buf);
+		strcpy_s(tvar[tvar_index - 1], 22, newstr);
+		free(newstr);
+	}
+#endif
 }
 
 void NACT::initialize_console()
diff --git a/src/sys/ags_text.cpp b/src/sys/ags_text.cpp
index 36810b0..54432db 100644
--- a/src/sys/ags_text.cpp
+++ b/src/sys/ags_text.cpp
@@ -4,6 +4,7 @@
 	[ AGS - text ]
 */
 
+#include <string.h>
 #include "ags.h"
 #include "s2utbl.h"
 
@@ -542,6 +543,93 @@ void ags_setAntialiasedStringMode(int on) {
 int sjis2unicode(int byte1, int byte2) {
 	return s2u[byte1 - 0x80][byte2 - 0x40];
 }
+
+char* sjis2utf(char* str) {
+	unsigned char* src = (unsigned char*)str;
+	unsigned char* dst = (unsigned char*)malloc(strlen(str) * 3 + 1);
+	unsigned char* dstp = dst;
+
+	while (*src) {
+		if (*src <= 0x7f) {
+			*dstp++ = *src++;
+			continue;
+		}
+
+		int c;
+		if (*src >= 0xa0 && *src <= 0xdf) {
+			c = 0xff60 + *src - 0xa0;
+			src++;
+		} else {
+			c = s2u[*src - 0x80][*(src+1) - 0x40];
+			src += 2;
+		}
+
+		if (c <= 0x7f) {
+			*dstp++ = c;
+		} else if (c <= 0x7ff) {
+			*dstp++ = 0xc0 | c >> 6;
+			*dstp++ = 0x80 | (c & 0x3f);
+		} else {
+			*dstp++ = 0xe0 | c >> 12;
+			*dstp++ = 0x80 | (c >> 6 & 0x3f);
+			*dstp++ = 0x80 | (c & 0x3f);
+		}
+	}
+	*dstp = '\0';
+	return (char*)dst;
+}
+
+static int unicode_to_sjis(int u) {
+	for (int b1 = 0x80; b1 <= 0xff; b1++) {
+		if (b1 >= 0xa0 && b1 <= 0xdf)
+			continue;
+		for (int b2 = 0x40; b2 <= 0xff; b2++) {
+			if (u == s2u[b1 - 0x80][b2 - 0x40])
+				return b1 << 8 | b2;
+		}
+	}
+	return 0;
+}
+
+char* utf2sjis(char* str) {
+	unsigned char* src = (unsigned char*)str;
+	unsigned char* dst = (unsigned char*)malloc(strlen(str) + 1);
+	unsigned char* dstp = dst;
+
+	while (*src) {
+		if (*src <= 0x7f) {
+			*dstp++ = *src++;
+			continue;
+		}
+
+		int u;
+		if (*src <= 0xdf) {
+			u = (src[0] & 0x1f) << 6 | (src[1] & 0x3f);
+			src += 2;
+		} else if (*src <= 0xef) {
+			u = (src[0] & 0xf) << 12 | (src[1] & 0x3f) << 6 | (src[2] & 0x3f);
+			src += 3;
+		} else {
+			*dstp++ = '?';
+			do src++; while ((*src & 0xc0) == 0x80);
+			continue;
+		}
+
+		if (u > 0xff60 && u <= 0xff9f) {
+			*dstp++ = u - 0xff60 + 0xa0;
+		} else {
+			int c = unicode_to_sjis(u);
+			if (c) {
+				*dstp++ = c >> 8;
+				*dstp++ = c & 0xff;
+			} else {
+				*dstp++ = '?';
+			}
+		}
+	}
+	*dstp = '\0';
+	return (char*)dst;
+}
 #endif
 
 }