diff --git a/src/shrpx_downstream.cc b/src/shrpx_downstream.cc
index 2f55e5d6..d9325699 100644
--- a/src/shrpx_downstream.cc
+++ b/src/shrpx_downstream.cc
@@ -127,7 +127,7 @@ Downstream::Downstream(Upstream *upstream, MemchunkPool *mcpool,
       request_http2_expect_body_(false), chunked_response_(false),
       response_connection_close_(false), response_header_key_prev_(false),
       response_trailer_key_prev_(false), expect_final_response_(false),
-      request_pending_(false), request_headers_dirty_(false) {
+      request_pending_(false) {
 
   ev_timer_init(&upstream_rtimer_, &upstream_rtimeoutcb, 0.,
                 get_config()->stream_read_timeout);
@@ -1218,12 +1218,4 @@ bool Downstream::can_detach_downstream_connection() const {
          !response_connection_close_;
 }
 
-void Downstream::set_request_headers_dirty(bool f) {
-  request_headers_dirty_ = f;
-}
-
-bool Downstream::get_request_headers_dirty() const {
-  return request_headers_dirty_;
-}
-
 } // namespace shrpx
diff --git a/src/shrpx_downstream.h b/src/shrpx_downstream.h
index a12359fa..9139eb5d 100644
--- a/src/shrpx_downstream.h
+++ b/src/shrpx_downstream.h
@@ -127,8 +127,6 @@ public:
   void append_last_request_header_value(const char *data, size_t len);
   // Empties request headers.
   void clear_request_headers();
-  void set_request_headers_dirty(bool f);
-  bool get_request_headers_dirty() const;
 
   size_t get_request_headers_sum() const;
 
@@ -457,8 +455,6 @@ private:
   // has not been established or should be checked before use;
   // currently used only with HTTP/2 connection.
   bool request_pending_;
-  // true if we need to execute index_request_headers()
-  bool request_headers_dirty_;
 };
 
 } // namespace shrpx
diff --git a/src/shrpx_mruby.cc b/src/shrpx_mruby.cc
index aa3135dd..8e32387d 100644
--- a/src/shrpx_mruby.cc
+++ b/src/shrpx_mruby.cc
@@ -43,42 +43,49 @@ MRubyContext::MRubyContext(mrb_state *mrb, RProc *on_request_proc,
 
 MRubyContext::~MRubyContext() { mrb_close(mrb_); }
 
-int MRubyContext::run_on_request_proc(Downstream *downstream) {
-  if (!on_request_proc_) {
+namespace {
+int run_request_proc(mrb_state *mrb, Downstream *downstream, RProc *proc) {
+  if (!proc) {
     return 0;
   }
 
-  mrb_->ud = downstream;
+  MRubyAssocData data{downstream};
+
+  mrb->ud = &data;
 
   int rv = 0;
-  auto ai = mrb_gc_arena_save(mrb_);
+  auto ai = mrb_gc_arena_save(mrb);
 
-  auto res = mrb_run(mrb_, on_request_proc_, mrb_top_self(mrb_));
+  auto res = mrb_run(mrb, proc, mrb_top_self(mrb));
   (void)res;
 
-  if (mrb_->exc) {
+  if (mrb->exc) {
     rv = -1;
     auto error =
-        mrb_str_ptr(mrb_funcall(mrb_, mrb_obj_value(mrb_->exc), "inspect", 0));
+        mrb_str_ptr(mrb_funcall(mrb, mrb_obj_value(mrb->exc), "inspect", 0));
 
     LOG(ERROR) << "Exception caught while executing mruby code: "
                << error->as.heap.ptr;
-    mrb_->exc = 0;
+    mrb->exc = 0;
   }
 
-  mrb_->ud = nullptr;
+  mrb->ud = nullptr;
 
-  mrb_gc_arena_restore(mrb_, ai);
+  mrb_gc_arena_restore(mrb, ai);
 
-  if (downstream->get_request_headers_dirty()) {
-    downstream->set_request_headers_dirty(false);
+  if (data.request_headers_dirty) {
     downstream->index_request_headers();
   }
 
   return rv;
 }
+} // namespace
 
-int run_on_response_proc(Downstream *downstream) {
+int MRubyContext::run_on_request_proc(Downstream *downstream) {
+  return run_request_proc(mrb_, downstream, on_request_proc_);
+}
+
+int MRubyContext::run_on_response_proc(Downstream *downstream) {
   // TODO not implemented yet
   return 0;
 }
diff --git a/src/shrpx_mruby.h b/src/shrpx_mruby.h
index 6e0bc57e..6494d8f0 100644
--- a/src/shrpx_mruby.h
+++ b/src/shrpx_mruby.h
@@ -52,6 +52,11 @@ private:
   RProc *on_response_proc_;
 };
 
+struct MRubyAssocData {
+  Downstream *downstream;
+  bool request_headers_dirty;
+};
+
 RProc *compile(mrb_state *mrb, const char *filename);
 
 std::unique_ptr<MRubyContext> create_mruby_context();
diff --git a/src/shrpx_mruby_module.cc b/src/shrpx_mruby_module.cc
index fabb1c5d..9e0be077 100644
--- a/src/shrpx_mruby_module.cc
+++ b/src/shrpx_mruby_module.cc
@@ -26,21 +26,46 @@
 
 #include <mruby/variable.h>
 #include <mruby/string.h>
+#include <mruby/hash.h>
+#include <mruby/array.h>
 
 #include "shrpx_downstream.h"
+#include "shrpx_mruby.h"
 #include "util.h"
 
 namespace shrpx {
 
 namespace mruby {
 
+namespace {
+mrb_value create_headers_hash(mrb_state *mrb, const Headers &headers) {
+  auto hash = mrb_hash_new(mrb);
+
+  for (auto &hd : headers) {
+    if (hd.name.empty() || hd.name[0] == ':') {
+      continue;
+    }
+    auto key = mrb_str_new(mrb, hd.name.c_str(), hd.name.size());
+    auto ary = mrb_hash_get(mrb, hash, key);
+    if (mrb_nil_p(ary)) {
+      ary = mrb_ary_new(mrb);
+      mrb_hash_set(mrb, hash, key, ary);
+    }
+    mrb_ary_push(mrb, ary, mrb_str_new(mrb, hd.value.c_str(), hd.value.size()));
+  }
+
+  return hash;
+}
+} // namespace
+
 namespace {
 mrb_value request_init(mrb_state *mrb, mrb_value self) { return self; }
 } // namespace
 
 namespace {
 mrb_value request_get_path(mrb_state *mrb, mrb_value self) {
-  auto downstream = static_cast<Downstream *>(mrb->ud);
+  auto data = static_cast<MRubyAssocData *>(mrb->ud);
+  auto downstream = data->downstream;
   auto &path = downstream->get_request_path();
 
   return mrb_str_new(mrb, path.c_str(), path.size());
@@ -49,7 +74,8 @@ mrb_value request_get_path(mrb_state *mrb, mrb_value self) {
 
 namespace {
 mrb_value request_set_path(mrb_state *mrb, mrb_value self) {
-  auto downstream = static_cast<Downstream *>(mrb->ud);
+  auto data = static_cast<MRubyAssocData *>(mrb->ud);
+  auto downstream = data->downstream;
 
   const char *path;
   mrb_int pathlen;
@@ -66,100 +92,51 @@ mrb_value request_set_path(mrb_state *mrb, mrb_value self) {
 
 namespace {
 mrb_value request_get_headers(mrb_state *mrb, mrb_value self) {
-  auto headers = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "RequestHeaders"));
-  if (mrb_nil_p(headers)) {
-    auto module = mrb_module_get(mrb, "Nghttpx");
-    auto headers_class = mrb_class_get_under(mrb, module, "RequestHeaders");
-    headers = mrb_obj_new(mrb, headers_class, 0, nullptr);
-    mrb_iv_set(mrb, self, mrb_intern_lit(mrb, "RequestHeaders"), headers);
-  }
-  return headers;
+  auto data = static_cast<MRubyAssocData *>(mrb->ud);
+  auto downstream = data->downstream;
+  return create_headers_hash(mrb, downstream->get_request_headers());
 }
 } // namespace
 
 namespace {
-mrb_value headers_init(mrb_state *mrb, mrb_value self) { return self; }
-} // namespace
+mrb_value request_set_header(mrb_state *mrb, mrb_value self) {
+  auto data = static_cast<MRubyAssocData *>(mrb->ud);
+  auto downstream = data->downstream;
 
-namespace {
-mrb_value request_headers_get(mrb_state *mrb, mrb_value self) {
-  auto downstream = static_cast<Downstream *>(mrb->ud);
-
-  mrb_value key;
-  mrb_get_args(mrb, "o", &key);
-
-  key = mrb_funcall(mrb, key, "downcase", 0);
-
-  if (RSTRING_LEN(key) == 0) {
-    return key;
-  }
-
-  auto hd = downstream->get_request_header(
-      std::string(RSTRING_PTR(key), RSTRING_LEN(key)));
-
-  if (hd == nullptr) {
-    return mrb_nil_value();
-  }
-
-  return mrb_str_new(mrb, hd->value.c_str(), hd->value.size());
-}
-} // namespace
-
-namespace {
-mrb_value request_headers_set(mrb_state *mrb, mrb_value self, bool repl) {
-  auto downstream = static_cast<Downstream *>(mrb->ud);
-
-  mrb_value key, value;
-  mrb_get_args(mrb, "oo", &key, &value);
-
-  key = mrb_funcall(mrb, key, "downcase", 0);
+  mrb_value key, values;
+  mrb_get_args(mrb, "oo", &key, &values);
 
   if (RSTRING_LEN(key) == 0) {
     mrb_raise(mrb, E_RUNTIME_ERROR, "empty key is not allowed");
   }
 
-  if (repl) {
-    for (auto &hd : downstream->get_request_headers()) {
-      if (util::streq(std::begin(hd.name), hd.name.size(), RSTRING_PTR(key),
-                      RSTRING_LEN(key))) {
-        hd.name = "";
-      }
+  key = mrb_funcall(mrb, key, "downcase", 0);
+
+  // making name empty will effectively delete header fields
+  for (auto &hd : downstream->get_request_headers()) {
+    if (util::streq(std::begin(hd.name), hd.name.size(), RSTRING_PTR(key),
+                    RSTRING_LEN(key))) {
+      hd.name = "";
     }
   }
 
-  downstream->add_request_header(
-      std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
-      std::string(RSTRING_PTR(value), RSTRING_LEN(value)));
+  if (mrb_obj_is_instance_of(mrb, values, mrb->array_class)) {
+    auto n = mrb_ary_len(mrb, values);
+    for (int i = 0; i < n; ++i) {
+      auto value = mrb_ary_entry(values, i);
+      downstream->add_request_header(
+          std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
+          std::string(RSTRING_PTR(value), RSTRING_LEN(value)));
+    }
+  } else {
+    downstream->add_request_header(
+        std::string(RSTRING_PTR(key), RSTRING_LEN(key)),
+        std::string(RSTRING_PTR(values), RSTRING_LEN(values)));
+  }
 
-  downstream->set_request_headers_dirty(true);
+  data->request_headers_dirty = true;
 
-  return key;
-}
-} // namespace
-
-namespace {
-mrb_value request_headers_set(mrb_state *mrb, mrb_value self) {
-  return request_headers_set(mrb, self, true);
-}
-} // namespace
-
-namespace {
-mrb_value request_headers_add(mrb_state *mrb, mrb_value self) {
-  return request_headers_set(mrb, self, false);
-}
-} // namespace
-
-namespace {
-void init_headers_class(mrb_state *mrb, RClass *module, const char *name,
-                        mrb_func_t get, mrb_func_t set, mrb_func_t add) {
-  auto headers_class =
-      mrb_define_class_under(mrb, module, name, mrb->object_class);
-
-  mrb_define_method(mrb, headers_class, "initialize", headers_init,
-                    MRB_ARGS_NONE());
-  mrb_define_method(mrb, headers_class, "get", get, MRB_ARGS_REQ(1));
-  mrb_define_method(mrb, headers_class, "set", set, MRB_ARGS_REQ(2));
-  mrb_define_method(mrb, headers_class, "add", add, MRB_ARGS_REQ(2));
+  return mrb_nil_value();
 }
 } // namespace
 
@@ -176,15 +153,30 @@ void init_request_class(mrb_state *mrb, RClass *module) {
                     MRB_ARGS_REQ(1));
   mrb_define_method(mrb, request_class, "headers", request_get_headers,
                     MRB_ARGS_NONE());
+  mrb_define_method(mrb, request_class, "set_header", request_set_header,
+                    MRB_ARGS_REQ(2));
+}
+} // namespace
 
-  init_headers_class(mrb, module, "RequestHeaders", request_headers_get,
-                     request_headers_set, request_headers_add);
+namespace {
+mrb_value run(mrb_state *mrb, mrb_value self) {
+  mrb_value b;
+  mrb_get_args(mrb, "&", &b);
+
+  auto module = mrb_module_get(mrb, "Nghttpx");
+  auto request_class = mrb_class_get_under(mrb, module, "Request");
+  auto request = mrb_obj_new(mrb, request_class, 0, nullptr);
+
+  std::array<mrb_value, 1> args{{request}};
+  return mrb_yield_argv(mrb, b, args.size(), args.data());
 }
 } // namespace
 
 void init_module(mrb_state *mrb) {
   auto module = mrb_define_module(mrb, "Nghttpx");
 
+  mrb_define_class_method(mrb, module, "run", run, MRB_ARGS_BLOCK());
+
   init_request_class(mrb, module);
 }