diff --git a/sds/src/scanner/regex_rule/config.rs b/sds/src/scanner/regex_rule/config.rs
index 7db7f477..4e7e762e 100644
--- a/sds/src/scanner/regex_rule/config.rs
+++ b/sds/src/scanner/regex_rule/config.rs
@@ -250,6 +250,7 @@ pub enum SecondaryValidator {
     ItalianNationalIdChecksum,
     JapanCorporateNumberChecksum,
     JapanDrivingLicenseChecksum,
+    JapanMyNumberChecksum,
     JwtClaimsValidator {
         config: JwtClaimsValidatorConfig,
     },
diff --git a/sds/src/secondary_validation/japan_my_number_checksum.rs b/sds/src/secondary_validation/japan_my_number_checksum.rs
new file mode 100644
index 00000000..9049f4de
--- /dev/null
+++ b/sds/src/secondary_validation/japan_my_number_checksum.rs
@@ -0,0 +1,67 @@
+use crate::secondary_validation::{Validator, validate_mod11_weighted_checksum};
+
+/// Check digit defined by Article 5 of Japanese ordinance No. 85:
+/// https://laws.e-gov.go.jp/law/426M60000008085#Mp-At_5
+pub struct JapanMyNumberChecksum;
+
+const WEIGHTS: &[u32; 11] = &[6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2];
+
+impl Validator for JapanMyNumberChecksum {
+    fn is_valid_match(&self, regex_match: &str) -> bool {
+        validate_mod11_weighted_checksum(regex_match, WEIGHTS, |remainder| {
+            Some(if remainder <= 1 { 0 } else { 11 - remainder })
+        })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::secondary_validation::{JapanMyNumberChecksum, Validator};
+
+    #[test]
+    fn test_published_japan_my_numbers() {
+        // TKC examples:
+        // https://www.prft.tkc.co.jp/SystemqaCPNYFree/Main/QaItem.aspx?category_id=2044&item_id=83412&system_id=260
+        assert!(JapanMyNumberChecksum.is_valid_match("123456789018"));
+        assert!(!JapanMyNumberChecksum.is_valid_match("923456789018"));
+    }
+
+    #[test]
+    fn test_generated_japan_my_numbers() {
+        // Generated fixtures from https://box4.dev/en/japan/my-number-generator
+        for number in [
+            "6637 6256 7333",
+            "8834 6653 3261",
+            "7680 7456 4211",
+            "3385 0214 0532",
+            "5800 0094 7110",
+        ] {
+            assert!(JapanMyNumberChecksum.is_valid_match(number), "{number}");
+            assert!(JapanMyNumberChecksum.is_valid_match(&number.replace(' ', "")));
+        }
+    }
+
+    #[test]
+    fn test_incorrect_check_digit() {
+        assert!(!JapanMyNumberChecksum.is_valid_match("123456789012"));
+        assert!(!JapanMyNumberChecksum.is_valid_match("1234 5678 9012"));
+    }
+
+    #[test]
+    fn test_incorrect_digit_count() {
+        for number in ["", "12345678901", "1234567890180"] {
+            assert!(!JapanMyNumberChecksum.is_valid_match(number), "{number}");
+        }
+    }
+
+    #[test]
+    fn test_zero_check_digit_for_small_remainders() {
+        // Synthetic arithmetic cases: sums 11 and 12 give remainders 0 and 1.
+        for number in ["000000000140", "000000000060"] {
+            assert!(JapanMyNumberChecksum.is_valid_match(number), "{number}");
+        }
+        for number in ["000000000141", "000000000061"] {
+            assert!(!JapanMyNumberChecksum.is_valid_match(number), "{number}");
+        }
+    }
+}
diff --git a/sds/src/secondary_validation/mod.rs b/sds/src/secondary_validation/mod.rs
index d318d782..22422ac7 100644
--- a/sds/src/secondary_validation/mod.rs
+++ b/sds/src/secondary_validation/mod.rs
@@ -31,6 +31,7 @@ mod iso_7064_checksum;
 mod italian_national_id_checksum;
 mod japan_corporate_number_checksum;
 mod japan_driving_license_checksum;
+mod japan_my_number_checksum;
 pub mod jwt_claims_validator;
 mod jwt_expiration_checker;
 mod latvia_national_id_checksum;
@@ -104,6 +105,7 @@ pub use crate::secondary_validation::iso_7064_checksum::{
 pub use crate::secondary_validation::italian_national_id_checksum::ItalianNationalIdChecksum;
 pub use crate::secondary_validation::japan_corporate_number_checksum::JapanCorporateNumberChecksum;
 pub use crate::secondary_validation::japan_driving_license_checksum::JapanDrivingLicenseChecksum;
+pub use crate::secondary_validation::japan_my_number_checksum::JapanMyNumberChecksum;
 pub use crate::secondary_validation::jwt_claims_validator::JwtClaimsValidator;
 pub use crate::secondary_validation::jwt_expiration_checker::JwtExpirationChecker;
 pub use crate::secondary_validation::latvia_national_id_checksum::LatviaNationalIdChecksum;
@@ -251,6 +253,7 @@ impl SecondaryValidator {
             SecondaryValidator::IbanChecker => Arc::new(IbanChecker),
             SecondaryValidator::IrishPpsChecksum => Arc::new(IrishPpsChecksum),
             SecondaryValidator::ItalianNationalIdChecksum => Arc::new(ItalianNationalIdChecksum),
+            SecondaryValidator::JapanMyNumberChecksum => Arc::new(JapanMyNumberChecksum),
             SecondaryValidator::JapanCorporateNumberChecksum => {
                 Arc::new(JapanCorporateNumberChecksum)
             }