diff --git a/cmd/find-often-tag-with/main.go b/cmd/find-often-tag-with/main.go
new file mode 100644
index 0000000..a1c4823
--- /dev/null
+++ b/cmd/find-often-tag-with/main.go
@@ -0,0 +1,101 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+
+	"github.com/sters/hugo-utilities/util"
+)
+
+type tagRelationHash string
+
+type tagRelation struct {
+	a     string
+	b     string
+	count int
+}
+
+func (s *tagRelation) Hash() tagRelationHash {
+	return tagRelationHash(s.a + "-" + s.b)
+}
+
+type tagRelations map[tagRelationHash]*tagRelation
+
+func (t tagRelations) append(tr *tagRelation) {
+	h := tr.Hash()
+	if tt, ok := t[h]; ok {
+		tt.count += tr.count
+		return
+	}
+
+	t[h] = tr
+}
+
+func main() {
+	t := flag.String("tag", "", "")
+	ff := flag.String("field", "tags", "")
+	basicFlags := util.ParseFlag()
+	flags := struct {
+		tag   string
+		field string
+	}{
+		tag:   strings.TrimSpace(*t),
+		field: strings.TrimSpace(*ff),
+	}
+
+	if flags.tag == "" {
+		fmt.Fprintf(os.Stderr, "Required tag argument\n\n")
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	contents, err := util.ReadAllContents(basicFlags.BaseDir)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed: %s", err)
+		os.Exit(1)
+	}
+
+	trs := tagRelations{}
+	for _, c := range contents {
+		tags := c.FrontMatter.GetStrings(flags.field)
+
+		for i, ta := range tags {
+			for j, tb := range tags {
+				if i == j {
+					continue
+				}
+				if ta != flags.tag {
+					continue
+				}
+
+				trs.append(&tagRelation{
+					a:     ta,
+					b:     tb,
+					count: 1,
+				})
+			}
+		}
+	}
+
+	sortedtrs := make([]*tagRelation, 0, len(trs))
+	for _, tr := range trs {
+		sortedtrs = append(sortedtrs, tr)
+	}
+
+	sort.Slice(sortedtrs, func(i, j int) bool {
+		if sortedtrs[i].count == sortedtrs[j].count {
+			if sortedtrs[i].a == sortedtrs[j].a {
+				return sortedtrs[i].b < sortedtrs[j].b
+			}
+			return sortedtrs[i].a < sortedtrs[j].a
+		}
+		return sortedtrs[i].count > sortedtrs[j].count
+	})
+
+	for _, tr := range sortedtrs {
+		fmt.Printf("(%s, %s) = %d\n", tr.a, tr.b, tr.count)
+	}
+}
diff --git a/util/flag.go b/util/flag.go
index 88658db..921e909 100644
--- a/util/flag.go
+++ b/util/flag.go
@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"strings"
 )
 
 type BasicFlag struct {
@@ -17,7 +18,7 @@ func ParseFlag() *BasicFlag {
 	if *dir == "" {
 		fmt.Fprintf(
 			os.Stderr,
-			"required dir argument\n\n",
+			"Required dir argument\n\n",
 		)
 		flag.Usage()
 
@@ -25,6 +26,6 @@ func ParseFlag() *BasicFlag {
 	}
 
 	return &BasicFlag{
-		BaseDir: *dir,
+		BaseDir: strings.TrimSpace(*dir),
 	}
 }