diff --git a/core/libs/prx/libSceRegMgr/CMakeLists.txt b/core/libs/prx/libSceRegMgr/CMakeLists.txt
new file mode 100644
index 0000000000..e10c382e33
--- /dev/null
+++ b/core/libs/prx/libSceRegMgr/CMakeLists.txt
@@ -0,0 +1,15 @@
+add_library(libSceRegMgr SHARED EXCLUDE_FROM_ALL Export.cpp)
+target_include_directories(libSceRegMgr PRIVATE ${LIBS_INCLUDE_DIR})
+configure_windows_unwind(libSceRegMgr)
+
+if(BUILD_TESTING)
+    add_test_executable(guest_regmgr_tests ${LIBS_INCLUDE_DIR}/tests/GuestRegMgr.cpp)
+    target_include_directories(guest_regmgr_tests PRIVATE ${LIBS_INCLUDE_DIR})
+    target_link_libraries(guest_regmgr_tests PRIVATE libSceRegMgr libc)
+    configure_windows_unwind(guest_regmgr_tests)
+    add_test(NAME guest_regmgr COMMAND guest_regmgr_tests)
+    if(WIN32)
+        set_tests_properties(guest_regmgr PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libSceRegMgr>")
+    endif()
+endif()
diff --git a/core/libs/prx/libSceRegMgr/Export.cpp b/core/libs/prx/libSceRegMgr/Export.cpp
new file mode 100644
index 0000000000..d71daed4b0
--- /dev/null
+++ b/core/libs/prx/libSceRegMgr/Export.cpp
@@ -0,0 +1,14 @@
+#include <cstdint>
+#include "prx/libc/include/General.hpp"
+
+extern "C" {
+
+std::int32_t APS5_VABI sceRegMgrNonSysGetInt(std::int64_t key, std::int32_t unk, std::int32_t* data) {
+    (void)key;
+    (void)unk;
+    (void)data;
+    NotImplemented_nid_no_patch(__func__);
+    return 0;
+}
+
+}
diff --git a/core/libs/tests/GuestRegMgr.cpp b/core/libs/tests/GuestRegMgr.cpp
new file mode 100644
index 0000000000..dfdf074535
--- /dev/null
+++ b/core/libs/tests/GuestRegMgr.cpp
@@ -0,0 +1,27 @@
+#include "prx/libc/include/general/VabiMacros.hpp"
+#include <cstdint>
+#include <cstdlib>
+#include <stdexcept>
+#include <string>
+
+extern "C" {
+std::int32_t APS5_VABI sceRegMgrNonSysGetInt(std::int64_t key, std::int32_t unk, std::int32_t* data);
+}
+
+static void Require(bool value) { if (!value) std::abort(); }
+
+template <typename TCall>
+static bool ReportsNotImplemented(const char* name, TCall call) {
+    try {
+        call();
+    } catch (const std::runtime_error& error) {
+        return std::string(error.what()) == std::string(name) + " not implemented";
+    }
+    return false;
+}
+
+int main() {
+    std::int32_t value = 0;
+    Require(ReportsNotImplemented("sceRegMgrNonSysGetInt", [&] { sceRegMgrNonSysGetInt(0, 0, &value); }));
+    Require(ReportsNotImplemented("sceRegMgrNonSysGetInt", [&] { sceRegMgrNonSysGetInt(-1, 1, nullptr); }));
+}
diff --git a/docs/dev/debt/libSceRegMgr.md b/docs/dev/debt/libSceRegMgr.md
new file mode 100644
index 0000000000..467ad2850e
--- /dev/null
+++ b/docs/dev/debt/libSceRegMgr.md
@@ -0,0 +1,5 @@
+# libSceRegMgr technical debt
+
+### Unknown function info
+
+- [sceRegMgrNonSysGetInt](../../../core/libs/prx/libSceRegMgr/Export.cpp) (libSceRegMgr, NID `dKeshzt29G4`) - imported by Astro Bot (PPSA21564), which fails to load without libSceRegMgr.prx (issue 4720); the `(int64_t key, int32_t unk, int32_t* data)` signature follows [ChonkyStation4](https://github.com/liuk7071/ChonkyStation4/blob/c101a23ecbc15e56c6e30d5dd24d3ed8880a957a/ChonkyStation4/OS/Libraries/SceRegMgr/SceRegMgr.cpp#L38-L47), not measured on a console, so every call throws