diff --git a/problems/data/009-replace-all-delimiters.json b/problems/data/009-replace-all-delimiters.json
new file mode 100644
index 0000000..8a2281e
--- /dev/null
+++ b/problems/data/009-replace-all-delimiters.json
@@ -0,0 +1,53 @@
+{
+  "id": "data-009",
+  "category": "data",
+  "difficulty": 2,
+  "start": [
+    "1;alice;active",
+    "2;bob;active",
+    "3;carol;inactive"
+  ],
+  "goal": [
+    "1,alice,active",
+    "2,bob,active",
+    "3,carol,inactive"
+  ],
+  "solutions": [
+    {
+      "keys": ":%s/;/,/g<CR>",
+      "optimal": true
+    },
+    {
+      "keys": ":1,3s/;/,/g<CR>"
+    }
+  ],
+  "tags": [
+    ":s",
+    "substitute",
+    "csv"
+  ],
+  "i18n": {
+    "ja": {
+      "title": "区切り文字を一括で置換する",
+      "description": "すべてのセミコロンをカンマに置き換えてください",
+      "hints": [
+        ":%s/old/new/g は全行のすべての一致を置換する"
+      ],
+      "notes": [
+        ":%s/;/,/g の % は全行、末尾の g は行内のすべての一致を意味する",
+        ":1,3s/;/,/g のように範囲を数字で指定しても同じ結果になる"
+      ]
+    },
+    "en": {
+      "title": "Replace every delimiter",
+      "description": "Replace every semicolon with a comma",
+      "hints": [
+        ":%s/old/new/g substitutes every match on every line"
+      ],
+      "notes": [
+        "In :%s/;/,/g the % means all lines and the trailing g means every match in each line",
+        "An explicit range like :1,3s/;/,/g does the same thing"
+      ]
+    }
+  }
+}
diff --git a/problems/data/010-strip-trailing-comma.json b/problems/data/010-strip-trailing-comma.json
new file mode 100644
index 0000000..94891b7
--- /dev/null
+++ b/problems/data/010-strip-trailing-comma.json
@@ -0,0 +1,54 @@
+{
+  "id": "data-010",
+  "category": "data",
+  "difficulty": 2,
+  "start": [
+    "id,name,",
+    "1,alice,",
+    "2,bob,"
+  ],
+  "goal": [
+    "id,name",
+    "1,alice",
+    "2,bob"
+  ],
+  "solutions": [
+    {
+      "keys": ":%s/,$//<CR>",
+      "optimal": true
+    },
+    {
+      "keys": ":%normal $x<CR>"
+    }
+  ],
+  "tags": [
+    ":s",
+    "substitute",
+    "regex",
+    "csv"
+  ],
+  "i18n": {
+    "ja": {
+      "title": "行末のカンマを消す",
+      "description": "各行の末尾のカンマを削除してください",
+      "hints": [
+        "置換パターンの $ は行末にマッチする"
+      ],
+      "notes": [
+        ":%s/,$// は全行の行末カンマだけを空文字に置換する",
+        ":%normal $x で全行に対して $x（行末へ移動して1文字削除）を実行しても同じ"
+      ]
+    },
+    "en": {
+      "title": "Strip the trailing comma",
+      "description": "Delete the trailing comma on every line",
+      "hints": [
+        "$ in a substitute pattern matches the end of the line"
+      ],
+      "notes": [
+        ":%s/,$// replaces only the end-of-line comma with nothing on every line",
+        ":%normal $x runs $x (jump to end of line, delete one char) on every line for the same result"
+      ]
+    }
+  }
+}
diff --git a/problems/data/011-update-status-values.json b/problems/data/011-update-status-values.json
new file mode 100644
index 0000000..73b5acc
--- /dev/null
+++ b/problems/data/011-update-status-values.json
@@ -0,0 +1,52 @@
+{
+  "id": "data-011",
+  "category": "data",
+  "difficulty": 2,
+  "start": [
+    "1,alice,pending",
+    "2,bob,done",
+    "3,carol,pending"
+  ],
+  "goal": [
+    "1,alice,done",
+    "2,bob,done",
+    "3,carol,done"
+  ],
+  "solutions": [
+    {
+      "keys": ":%s/pending/done/<CR>",
+      "optimal": true
+    },
+    {
+      "keys": ":%s/pending/done/g<CR>"
+    }
+  ],
+  "tags": [
+    ":s",
+    "substitute"
+  ],
+  "i18n": {
+    "ja": {
+      "title": "ステータスをまとめて更新する",
+      "description": "すべての pending を done に置き換えてください",
+      "hints": [
+        "1行に1回しか出てこない語なら g フラグは要らない"
+      ],
+      "notes": [
+        ":%s/pending/done/ は各行の最初の一致だけを置換する。1行1回なのでこれで十分",
+        "g フラグを付けても結果は同じだが、この行では不要"
+      ]
+    },
+    "en": {
+      "title": "Update the status values",
+      "description": "Replace every 'pending' with 'done'",
+      "hints": [
+        "The g flag is unnecessary when the word appears once per line"
+      ],
+      "notes": [
+        ":%s/pending/done/ substitutes the first match on each line, which is enough here",
+        "Adding the g flag gives the same result but is not needed on these lines"
+      ]
+    }
+  }
+}
diff --git a/problems/data/012-delete-blank-rows.json b/problems/data/012-delete-blank-rows.json
new file mode 100644
index 0000000..7b5aca6
--- /dev/null
+++ b/problems/data/012-delete-blank-rows.json
@@ -0,0 +1,55 @@
+{
+  "id": "data-012",
+  "category": "data",
+  "difficulty": 3,
+  "start": [
+    "1,alice",
+    "",
+    "2,bob",
+    "",
+    "3,carol"
+  ],
+  "goal": [
+    "1,alice",
+    "2,bob",
+    "3,carol"
+  ],
+  "solutions": [
+    {
+      "keys": ":g/^$/d<CR>",
+      "optimal": true
+    },
+    {
+      "keys": "jddjdd"
+    }
+  ],
+  "tags": [
+    ":g",
+    "global",
+    "dd"
+  ],
+  "i18n": {
+    "ja": {
+      "title": "空行を取り除く",
+      "description": "データの間にある空行をすべて削除してください",
+      "hints": [
+        ":g/pattern/d はパターンに一致する行をすべて削除する"
+      ],
+      "notes": [
+        ":g/^$/d は空行（行頭がすぐ行末の行）だけを対象に d を実行する",
+        "空行が少なければ j で移動して dd を繰り返してもよい"
+      ]
+    },
+    "en": {
+      "title": "Remove the blank rows",
+      "description": "Delete every blank line between the data rows",
+      "hints": [
+        ":g/pattern/d deletes every line matching the pattern"
+      ],
+      "notes": [
+        ":g/^$/d runs d on every empty line (start of line immediately followed by end of line)",
+        "With only a couple of blanks you can also just move with j and repeat dd"
+      ]
+    }
+  }
+}