diff --git a/chunihook/jvs.c b/chunihook/jvs.c
new file mode 100644
index 0000000..b505740
--- /dev/null
+++ b/chunihook/jvs.c
@@ -0,0 +1,96 @@
+#include <windows.h>
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "board/io3.h"
+
+#include "jvs/jvs-bus.h"
+
+#include "nu/jvs.h"
+
+#include "util/dprintf.h"
+
+static void chunithm_jvs_read_switches(void *ctx, struct io3_switch_state *out);
+static uint16_t chunithm_jvs_consume_coins(void *ctx, uint8_t slot_no);
+
+static const struct io3_ops chunithm_jvs_io3_ops = {
+    .read_switches  = chunithm_jvs_read_switches,
+    .consume_coins  = chunithm_jvs_consume_coins,
+};
+
+static struct io3 chunithm_jvs_io3;
+static size_t chunithm_jvs_rise_pos;
+static bool chunithm_jvs_coin;
+
+void chunithm_jvs_init(void)
+{
+    io3_init(&chunithm_jvs_io3, NULL, &chunithm_jvs_io3_ops, NULL);
+    jvs_attach(&chunithm_jvs_io3.jvs);
+}
+
+static void chunithm_jvs_read_switches(void *ctx, struct io3_switch_state *out)
+{
+    assert(out != NULL);
+
+    /* Update simulated raise/lower state */
+
+    if (GetAsyncKeyState(VK_SPACE)) {
+        if (chunithm_jvs_rise_pos < 6) {
+            chunithm_jvs_rise_pos++;
+        }
+    } else {
+        if (chunithm_jvs_rise_pos > 0) {
+            chunithm_jvs_rise_pos--;
+        }
+    }
+
+    /* Render the state. Every case falls through, this is intentional. */
+
+    out->p1 = 0;
+    out->p2 = 0;
+
+    switch (chunithm_jvs_rise_pos) {
+    case 0: out->p2 |= 0x0020;
+    case 1: out->p1 |= 0x0020;
+    case 2: out->p2 |= 0x0010;
+    case 3: out->p1 |= 0x0010;
+    case 4: out->p2 |= 0x0008;
+    case 5: out->p1 |= 0x0008;
+    }
+
+    /* Update test/service buttons */
+
+    if (GetAsyncKeyState('1')) {
+        out->system = 0x80;
+    } else {
+        out->system = 0;
+    }
+
+    if (GetAsyncKeyState('2')) {
+        out->p1 |= 0x4000;
+    }
+}
+
+static uint16_t chunithm_jvs_consume_coins(void *ctx, uint8_t slot_no)
+{
+    if (slot_no > 0) {
+        return 0;
+    }
+
+    if (GetAsyncKeyState('3')) {
+        if (chunithm_jvs_coin) {
+            return 0;
+        } else {
+            dprintf("Chunithm JVS: Coin drop\n");
+            chunithm_jvs_coin = true;
+
+            return 1;
+        }
+    } else {
+        chunithm_jvs_coin = false;
+
+        return 0;
+    }
+}
diff --git a/chunihook/jvs.h b/chunihook/jvs.h
new file mode 100644
index 0000000..72d8921
--- /dev/null
+++ b/chunihook/jvs.h
@@ -0,0 +1,3 @@
+#pragma once
+
+void chunithm_jvs_init(void);
diff --git a/chunihook/meson.build b/chunihook/meson.build
index 1e9c138..5cf005c 100644
--- a/chunihook/meson.build
+++ b/chunihook/meson.build
@@ -16,5 +16,7 @@ shared_library(
         util_lib,
     ],
     sources : [
+        'jvs.c',
+        'jvs.h',
     ],
 )