https://s.tonsky.me/karabiner/karabiner.json

karabiner.json

{
  "title": "Diamond Cursor",
  "rules": [
    {
      "description": "Change fn + I/J/K/L to Arrow Keys",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "i",
            "modifiers": {
              "mandatory": [
                "fn"
              ],
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "up_arrow"
            }
          ]
        },
        {
          "type": "basic",
          "from": {
            "key_code": "j",
            "modifiers": {
              "mandatory": [
                "fn"
              ],
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "left_arrow"
            }
          ]
        },
        {
          "type": "basic",
          "from": {
            "key_code": "k",
            "modifiers": {
              "mandatory": [
                "fn"
              ],
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "down_arrow"
            }
          ]
        },
        {
          "type": "basic",
          "from": {
            "key_code": "l",
            "modifiers": {
              "mandatory": [
                "fn"
              ],
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "right_arrow"
            }
          ]
        }
      ]
    },
    {
      "description": "Change fn + H to Delete",
      "manipulators": [
        {
          "type": "basic",
          "from": {
            "key_code": "h",
            "modifiers": {
              "mandatory": [
                "fn"
              ],
              "optional": [
                "any"
              ]
            }
          },
          "to": [
            {
              "key_code": "delete_or_backspace"
            }
          ]
        }
      ]
    }
  ]
}