diff --git a/lib/d2/backbone.ex b/lib/d2/backbone.ex
new file mode 100644
index 0000000..19ea4fb
--- /dev/null
+++ b/lib/d2/backbone.ex
@@ -0,0 +1,59 @@
+defmodule ExPlain.D2.Backbone do
+  @moduledoc """
+  Module to create backbone diagram
+  """
+  alias ExPlain.Reader.ModuleUnit
+
+  @spec create_diagram(ModuleUnit.t()) :: String.t()
+  def create_diagram(%ModuleUnit{
+        name: module_name,
+        public_functions: public_functions,
+        private_functions: private_functions
+      }) do
+    classes = get_backbone_class()
+    header = get_header_title(module_name)
+    public_functions_boxes = get_public_functions_boxes(public_functions)
+    private_functions_boxes = get_private_functions_boxes(private_functions)
+
+    classes <> header <> public_functions_boxes <> private_functions_boxes
+  end
+
+  defp get_public_functions_boxes(public_functions) do
+    for fun <- public_functions, into: "", do: "#{fun}.class: public \n"
+  end
+
+  defp get_private_functions_boxes(private_functions) do
+    for fun <- private_functions, into: "", do: "#{fun}.class: private\n"
+  end
+
+  defp get_header_title(module_name) do
+    """
+    explanation: |md
+      # #{module_name}
+    |
+    grid-columns: 3
+    """
+  end
+
+  defp get_backbone_class do
+    """
+      classes: {
+        public: {
+          style: {
+            stroke-width: 0
+            fill: "#85b4ff"
+            shadow: true
+            border-radius: 5
+          }
+        }
+
+        private: {
+          style: {
+            fill: "#fff585"
+            stroke: "#F69E03"
+          }
+        }
+      }
+    """
+  end
+end
diff --git a/lib/d2/d2.ex b/lib/d2/d2.ex
new file mode 100644
index 0000000..47f95a2
--- /dev/null
+++ b/lib/d2/d2.ex
@@ -0,0 +1,7 @@
+defmodule ExPlain.D2 do
+  @moduledoc """
+  Module to convert data into D2 diagrams
+  """
+
+  ### ExPlain Diagram I Module backbone diagram
+end
diff --git a/lib/reader/module_unit.ex b/lib/reader/module_unit.ex
new file mode 100644
index 0000000..b8a6d1e
--- /dev/null
+++ b/lib/reader/module_unit.ex
@@ -0,0 +1,15 @@
+defmodule ExPlain.Reader.ModuleUnit do
+  @moduledoc """
+  Struct for module unit
+  """
+  @type t() :: %__MODULE__{}
+  defstruct [:name, :public_functions, :private_functions]
+
+  def new(name, public_functions \\ [], private_functions \\ []) do
+    %__MODULE__{
+      name: name,
+      public_functions: public_functions,
+      private_functions: private_functions
+    }
+  end
+end
diff --git a/test/module_unit_test.exs b/test/module_unit_test.exs
new file mode 100644
index 0000000..784ad45
--- /dev/null
+++ b/test/module_unit_test.exs
@@ -0,0 +1,8 @@
+defmodule ExPlain.Reader.ModuleUnitTest do
+  use ExUnit.Case
+  alias ExPlain.Reader.ModuleUnit
+
+  test "create a module unit struct" do
+    assert %ModuleUnit{name: "MyModule"} = ModuleUnit.new("MyModule")
+  end
+end