diff --git a/syamauchi/src/C068.java b/syamauchi/src/C068.java
new file mode 100644
index 0000000000000000000000000000000000000000..53f0dbc23bb823a49635c54c5ede4b1fc3eda3bc
--- /dev/null
+++ b/syamauchi/src/C068.java
@@ -0,0 +1,81 @@
+package src;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+
+public class C068 {
+
+  // 復号するときに使う文字列
+  static String[] ALPHABET = {
+      "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S",
+      "T", "U", "V", "W", "X", "Y", "Z"
+  };
+
+  // アルファベットの数
+  static int ALPHABET_NUMBER = 26;
+
+  public static void main(String[] args) {
+    final Scanner sc = new Scanner(System.in);
+
+    final C068 decrypted = new C068();
+    System.out.println(decrypted.decodeLetter(sc.nextInt(), sc.next()));
+    sc.close();
+  }
+
+  // 解読した文章を出力
+  public String decodeLetter(final int decodeNumber, final String codeString) {
+    final String[] encryptedText = codeString.split("");
+    final String decryptedText = decode(decodeNumber, encryptedText);
+    return decryptedText;
+  }
+
+  // 解読
+  public String decode(final int decodeNumber, final String[] code) {
+    final StringBuilder decrypedText = new StringBuilder();
+    final List<String> alphabetList = Arrays.asList(ALPHABET);
+    for (int i = 0; i < code.length; i++) {
+      final int codeNumber = alphabetList.indexOf(code[i]);
+      // 配列のインデックスが0or偶数の時は逆方向にずらす
+      if (i % 2 == 0) {
+        decrypedText.append(reverceShiftCode(codeNumber, decodeNumber));
+        // インデックスが奇数の時は順方向にずらす
+      } else {
+        decrypedText.append(shiftCode(codeNumber, decodeNumber));
+      }
+    }
+    return decrypedText.toString();
+  }
+
+  // 順方向に文字をずらす
+  public String shiftCode(final int codeNumber, final int decodeNumber) {
+    // decodeNumber分文字をずらしたときのインデックス番号
+    final int corresponceNumber = codeNumber + decodeNumber;
+    final int number;
+    // 対応表の要素数より多い場合
+    if (corresponceNumber >= ALPHABET_NUMBER) {
+      number = corresponceNumber - ALPHABET_NUMBER;
+      return ALPHABET[number];
+
+    } else {
+      number = corresponceNumber;
+      return ALPHABET[number];
+    }
+  }
+
+  // 逆方向に文字をずらす
+  public String reverceShiftCode(final int codeNumber, final int decodeNumber) {
+    // decodeNumber分文字をずらしたときのインデックス番号
+    final int corresponceNumber = codeNumber - decodeNumber;
+    final int number;
+    // インデックスがマイナスになってしまう場合
+    if (corresponceNumber < 0) {
+      number = ALPHABET_NUMBER + corresponceNumber;
+      return ALPHABET[number];
+    } else {
+      number = corresponceNumber;
+      return ALPHABET[number];
+    }
+  }
+
+}
diff --git a/syamauchi/test/C068Test.java b/syamauchi/test/C068Test.java
new file mode 100644
index 0000000000000000000000000000000000000000..06fb63a20f71c9c09cbc51a4d9636baacf5ebcc5
--- /dev/null
+++ b/syamauchi/test/C068Test.java
@@ -0,0 +1,62 @@
+package test;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.MatcherAssert.*;
+import org.junit.Test;
+import src.C068;
+
+public class C068Test {
+
+  @Test
+  public void decodeで文字の解読ができるテスト() {
+    final C068 sut = new C068();
+    final String actual = sut.decodeLetter(4, "QEPG");
+    final String expected = "MILK";
+    assertThat(actual, is(expected));
+  }
+
+  // 1 <= decodeNumber <= 25
+  @Test
+  public void decodeNumberが1の時のテスト() {
+    final C068 sut = new C068();
+    final String actual = sut.decodeLetter(1, "QEPG");
+    final String expected = "PFOH";
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void decodeNumberが25の時のテスト() {
+    final C068 sut = new C068();
+    final String actual = sut.decodeLetter(25, "QEPG");
+    final String expected = "RDQF";
+    assertThat(actual, is(expected));
+  }
+
+  // 1<= codeString.length <= 500
+  @Test
+  public void codeStringの長さが１の時のテスト() {
+    final C068 sut = new C068();
+    final String actual = sut.decodeLetter(4, "Q");
+    final String expected = "M";
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void codeStringの長さが500の時のテスト() {
+    String str = "";
+    String exstr = "";
+    for (int i = 0; i < 500; i++) {
+      str += "A";
+      if (i == 0 || i % 2 == 0) {
+        exstr += "Z";
+      } else {
+        exstr += "B";
+      }
+    }
+
+    final C068 sut = new C068();
+    final String actual = sut.decodeLetter(1, str);
+    final String expected = exstr;
+    assertThat(actual, is(expected));
+  }
+}