diff --git a/apps/tests/phase99_json_loader_escape_trailing_backslash_min.hako b/apps/tests/phase99_json_loader_escape_trailing_backslash_min.hako
new file mode 100644
index 00000000..300d4358
--- /dev/null
+++ b/apps/tests/phase99_json_loader_escape_trailing_backslash_min.hako
@@ -0,0 +1,38 @@
+// Phase 99: json_loader escape with trailing backslash
+// Purpose: Exercise escape loop with incomplete escape sequence (trailing \).
+//          This fixture documents current behavior: trailing \ is silently ignored.
+
+static box Main {
+    main() {
+        // Input: "hello\" - string ending with backslash (incomplete escape)
+        local s = "\"hello\\\\"
+        local pos = 0
+        local i = pos
+
+        // Skip opening quote
+        if s.substring(i, i + 1) != "\"" { return "NG" }
+        i = i + 1
+
+        local out = ""
+        local n = s.length()
+
+        loop(i < n) {
+            local ch = s.substring(i, i + 1)
+            if ch == "\"" { break }
+
+            if ch == "\\" {
+                i = i + 1
+                if i < n {
+                    ch = s.substring(i, i + 1)
+                }
+            }
+
+            out = out + ch
+            i = i + 1
+        }
+
+        // Current behavior: trailing backslash is included in output
+        print(out)
+        return "OK"
+    }
+}
diff --git a/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_llvm_exe.sh b/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_llvm_exe.sh
new file mode 100644
index 00000000..8a7e3402
--- /dev/null
+++ b/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_llvm_exe.sh
@@ -0,0 +1,114 @@
+#!/bin/bash
+# Phase 99: escape trailing backslash fixture (LLVM EXE parity)
+
+source "$(dirname "$0")/../../../lib/test_runner.sh"
+export SMOKES_USE_PYVM=0
+require_env || exit 2
+
+# LLVM availability checks (graceful SKIP)
+if ! command -v llvm-config-18 &> /dev/null; then
+    test_skip "llvm-config-18 not found"; exit 0
+fi
+
+if ! "$NYASH_BIN" --help 2>&1 | grep -q "llvm"; then
+    test_skip "hakorune --backend llvm not available"; exit 0
+fi
+
+if ! python3 -c "import llvmlite" 2>/dev/null; then
+    test_skip "Python llvmlite not found"; exit 0
+fi
+
+FILEBOX_SO="$NYASH_ROOT/plugins/nyash-filebox-plugin/libnyash_filebox_plugin.so"
+MAPBOX_SO="$NYASH_ROOT/plugins/nyash-map-plugin/libnyash_map_plugin.so"
+
+check_plugins() {
+    python3 - "$FILEBOX_SO" "$MAPBOX_SO" <<'PY'
+import ctypes
+import os
+import sys
+names = ["FileBox", "MapBox"]
+paths = sys.argv[1:]
+failures = []
+for name, path in zip(names, paths):
+    if not os.path.isfile(path):
+        failures.append(f"[plugin/missing] {name}: {path}")
+        continue
+    try:
+        ctypes.CDLL(path)
+    except Exception as e:  # noqa: BLE001
+        failures.append(f"[plugin/dlopen] {name}: {path} ({e})")
+if failures:
+    print("\n".join(failures))
+    sys.exit(1)
+print("OK")
+PY
+}
+
+echo "[INFO] Checking plugin artifacts (FileBox/MapBox)"
+if ! CHECK_OUTPUT=$(check_plugins 2>&1); then
+    echo "$CHECK_OUTPUT"
+    echo "[INFO] Missing/broken plugin detected, running build-all (FileBox/MapBox)"
+    BUILD_LOG="/tmp/phase99_escape_trailing_backslash_plugin_build.log"
+    if ! bash "$NYASH_ROOT/tools/plugins/build-all.sh" nyash-filebox-plugin nyash-map-plugin >"$BUILD_LOG" 2>&1; then
+        echo "[FAIL] tools/plugins/build-all.sh failed for FileBox/MapBox"
+        tail -n 80 "$BUILD_LOG"
+        exit 1
+    fi
+    if ! CHECK_OUTPUT=$(check_plugins 2>&1); then
+        echo "$CHECK_OUTPUT"
+        echo "[FAIL] Plugin artifacts still missing or unloadable after build-all"
+        tail -n 80 "$BUILD_LOG"
+        exit 1
+    fi
+fi
+
+mkdir -p "$NYASH_ROOT/tmp"
+
+INPUT_HAKO="$NYASH_ROOT/apps/tests/phase99_json_loader_escape_trailing_backslash_min.hako"
+OUTPUT_EXE="$NYASH_ROOT/tmp/phase99_escape_trailing_backslash_llvm_exe"
+
+echo "[INFO] Building: $INPUT_HAKO → $OUTPUT_EXE"
+
+BUILD_LOG="/tmp/phase99_escape_trailing_backslash_build.log"
+if ! env NYASH_DISABLE_PLUGINS=0 "$NYASH_ROOT/tools/build_llvm.sh" "$INPUT_HAKO" -o "$OUTPUT_EXE" 2>&1 | tee "$BUILD_LOG"; then
+    echo "[FAIL] build_llvm.sh failed"
+    tail -n 80 "$BUILD_LOG"
+    exit 1
+fi
+
+if [ ! -x "$OUTPUT_EXE" ]; then
+    echo "[FAIL] Executable not created or not executable: $OUTPUT_EXE"
+    ls -la "$OUTPUT_EXE" 2>/dev/null || echo "File does not exist"
+    exit 1
+fi
+
+echo "[INFO] Executing: $OUTPUT_EXE"
+
+set +e
+OUTPUT=$(timeout "${RUN_TIMEOUT_SECS:-10}" env NYASH_DISABLE_PLUGINS=0 "$OUTPUT_EXE" 2>&1)
+EXIT_CODE=$?
+set -e
+
+if [ "$EXIT_CODE" -ne 0 ]; then
+    echo "[FAIL] Execution failed with exit code $EXIT_CODE"
+    echo "$OUTPUT" | tail -n 80
+    exit 1
+fi
+
+# Current behavior: trailing backslash is preserved in output
+CLEAN=$(printf "%s\n" "$OUTPUT" | grep -v "^\[" | grep -v "^$" | head -n 1 | tr -d '\r')
+EXPECTED="hello\\"
+
+echo "[INFO] CLEAN output:"
+echo "$CLEAN"
+
+if [ "$CLEAN" = "$EXPECTED" ]; then
+    test_pass "phase99_escape_trailing_backslash_llvm_exe: output matches expected (hello\\)"
+else
+    echo "[FAIL] Output mismatch"
+    echo "[INFO] Raw output (tail):"
+    echo "$OUTPUT" | tail -n 80
+    echo "[INFO] Expected:"
+    printf "%s\n" "$EXPECTED"
+    exit 1
+fi
diff --git a/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_vm.sh b/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_vm.sh
new file mode 100644
index 00000000..efaccc36
--- /dev/null
+++ b/tools/smokes/v2/profiles/integration/apps/phase99_escape_trailing_backslash_vm.sh
@@ -0,0 +1,57 @@
+#!/bin/bash
+# Phase 99: json_loader escape with trailing backslash (VM)
+#
+# Verifies current behavior: trailing backslash is included in output (best-effort).
+
+source "$(dirname "$0")/../../../lib/test_runner.sh"
+export SMOKES_USE_PYVM=0
+require_env || exit 2
+
+PASS_COUNT=0
+FAIL_COUNT=0
+RUN_TIMEOUT_SECS=${RUN_TIMEOUT_SECS:-10}
+
+INPUT="$NYASH_ROOT/apps/tests/phase99_json_loader_escape_trailing_backslash_min.hako"
+
+echo "[INFO] Phase 99: escape trailing backslash (VM) - $INPUT"
+
+set +e
+OUTPUT=$(timeout "$RUN_TIMEOUT_SECS" env \
+  NYASH_DISABLE_PLUGINS=1 \
+  HAKO_JOINIR_STRICT=1 \
+  "$NYASH_BIN" --backend vm "$INPUT" 2>&1)
+EXIT_CODE=$?
+set -e
+
+if [ "$EXIT_CODE" -eq 124 ]; then
+  echo "[FAIL] hakorune timed out (>${RUN_TIMEOUT_SECS}s)"
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+elif [ "$EXIT_CODE" -eq 0 ]; then
+  # Current behavior: trailing backslash is included in output
+  EXPECTED="hello\\"
+  CLEAN=$(printf "%s\n" "$OUTPUT" | grep -v "^\[" | grep -v "^$" | head -n 1 | tr -d '\r')
+  if [ "$CLEAN" = "$EXPECTED" ]; then
+    echo "[PASS] Output verified: hello\\ (trailing backslash preserved)"
+    PASS_COUNT=$((PASS_COUNT + 1))
+  else
+    echo "[FAIL] Unexpected output (expected: hello\\)"
+    echo "[INFO] output (tail):"
+    echo "$OUTPUT" | tail -n 50 || true
+    FAIL_COUNT=$((FAIL_COUNT + 1))
+  fi
+else
+  echo "[FAIL] hakorune failed with exit code $EXIT_CODE"
+  echo "[INFO] output (tail):"
+  echo "$OUTPUT" | tail -n 50 || true
+  FAIL_COUNT=$((FAIL_COUNT + 1))
+fi
+
+echo "[INFO] PASS: $PASS_COUNT, FAIL: $FAIL_COUNT"
+
+if [ "$FAIL_COUNT" -eq 0 ]; then
+  test_pass "phase99_escape_trailing_backslash_vm: Best-effort behavior verified"
+  exit 0
+else
+  test_fail "phase99_escape_trailing_backslash_vm: $FAIL_COUNT test(s) failed"
+  exit 1
+fi