--- b/config.def.h
+++ a/config.def.h
@@ -31,6 +31,7 @@
  * hostname            hostname                        NULL
  * ipv4                IPv4 address                    interface name (eth0)
  * ipv6                IPv6 address                    interface name (eth0)
+ * kanji               japanese day of week kanji      NULL
  * kernel_release      `uname -r`                      NULL
  * keyboard_indicators caps/num lock indicators        format string (c?n?)
  *                                                     see keyboard_indicators.c
--- a/components/kanji.c
+++ b/components/kanji.c
@@ -0,0 +1,13 @@
+/* See LICENSE file for copyright and license details. */
+#include <time.h>
+
+const char *
+kanji(const char *unused) {
+	char *kanji[]={"月","火","水","木","金","土","日"};
+	int map[]={0,3,2,5,0,3,5,1,4,6,2,4};
+	time_t t=time(NULL);
+	struct tm tm=*localtime(&t);
+	int m=tm.tm_mon+1,y=tm.tm_year+1900-(m<3);
+	int wd=(y+y/4-y/100+y/400+map[m-1]+tm.tm_mday)%7;
+	return kanji[wd-1];
+}
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,7 @@
 	components/entropy\
 	components/hostname\
 	components/ip\
+	components/kanji\
 	components/kernel_release\
 	components/keyboard_indicators\
 	components/keymap\
--- a/slstatus.h
+++ b/slstatus.h
@@ -31,6 +31,9 @@
 const char *ipv4(const char *interface);
 const char *ipv6(const char *interface);
 
+/* kanji */
+const char *kanji(const char *unused);
+
 /* kernel_release */
 const char *kernel_release(const char *unused);