diff --git a/docs/en/source/rpa/filespecification/inputfiles/interaction.rst b/docs/en/source/rpa/filespecification/inputfiles/interaction.rst
index cea2352..da3eaca 100644
--- a/docs/en/source/rpa/filespecification/inputfiles/interaction.rst
+++ b/docs/en/source/rpa/filespecification/inputfiles/interaction.rst
@@ -140,6 +140,6 @@ Usage rules
 
 -  The translation vectors need to be enclosed within the CellShape. If the range of ``r_x``, ``r_y``, or ``r_z`` exceeds the extent of ``x``, ``y``, or ``z`` dimension of CellShape, the program terminates with an error.
 
--  When ``mode.enable_spin_orbital`` is set to ``true``, the orbital indices of Transfer term are interpreted as the extended orbital indices including spin degree of freedom that ranges from 1 to :math:`2 N_\text{orbital}`. Otherwise, only the entries with the orbital indices from 1 to :math:`N_\text{orbital}` are taken into account.
+-  When ``mode.enable_spin_orbital`` is set to ``true``, the orbital indices of Transfer term are interpreted as the extended orbital indices including spin degree of freedom that ranges from 1 to :math:`2 N_\text{orbital}`, in which the indices :math:`1 \dots N_\text{orbital}` correspond to spin-up, and the indices :math:`N_\text{orbital}+1 \dots 2N_\text{orbital}` correspond to spin-down. Otherwise, only the entries with the orbital indices from 1 to :math:`N_\text{orbital}` are taken into account.
 
 .. raw:: latex
diff --git a/docs/ja/source/rpa/filespecification/inputfiles/interaction.rst b/docs/ja/source/rpa/filespecification/inputfiles/interaction.rst
index 50d86b9..ee67bf3 100644
--- a/docs/ja/source/rpa/filespecification/inputfiles/interaction.rst
+++ b/docs/ja/source/rpa/filespecification/inputfiles/interaction.rst
@@ -127,7 +127,7 @@
 -  並進ベクトルは全て ``CellShape`` 内に収まるとします。
    ``r_x``, ``r_y``, ``r_z`` の範囲が ``CellShape`` のx,y,z軸のサイズを超える場合はエラーで終了します。
 
--  ``mode.enable_spin_orbital`` が ``true`` の場合、Transfer項の軌道のインデックスはスピン自由度を含む一般化軌道インデックスと読み替え、1〜 :math:`2 N_\text{orbital}` の値をとります。 ``mode.enable_spin_orbital`` が ``false`` の場合は、インデックスの範囲が 1〜 :math:`N_\text{orbital}` の行のみ考慮します。
+-  ``mode.enable_spin_orbital`` が ``true`` の場合、Transfer項の軌道のインデックスはスピン自由度を含む一般化軌道インデックスと読み替え、1〜 :math:`2 N_\text{orbital}` の値をとります。1〜 :math:`N_\text{orbital}` が spin up、:math:`N_\text{orbital}+1` 〜 :math:`2 N_\text{orbital}` が spin down に対応します。 ``mode.enable_spin_orbital`` が ``false`` の場合は、インデックスの範囲が 1〜 :math:`N_\text{orbital}` の行のみ考慮します。
 
    
 .. raw:: latex