diff --git a/README.md b/README.md
index 9d6d78a..5965507 100644
--- a/README.md
+++ b/README.md
@@ -1,45 +1,45 @@
-# rrule-contrib
+# rrule-duration
 
-[![npm version](https://badge.fury.io/js/rrule-contrib.svg)](https://badge.fury.io/js/rrule-contrib)
+[![npm version](https://badge.fury.io/js/rrule-duration.svg)](https://badge.fury.io/js/rrule-duration)
 
-[RRule](https://github.com/jakubroztocil/rrule) related utilities.
+Add duration feature and time zone support to [RRule](https://github.com/jakubroztocil/rrule).
+
+# Features
+
+- Create events with duration and represent it with RRule
+- Time zone support, even separate start/end time
+- Dump duration as natural language
 
 # Install
 
 ```
-npm install --save rrule rrule-contrib
+npm install --save rrule rrule-duration
 ```
 
 Or if you use Yarn:
 
 ```
-yarn add rrule rrule-contrib
+yarn add rrule rrule-duration
 ```
 
-# Usage
-
-Currently the following classes are exported:
-
-- CalendarEvent
-
-TODO: add more functionality.
-
-## `CalendarEvent`
+# Basic Usage
 
 `CalendarEvent` class is intended to use `RRule` with calendar events. Basically an `event` is represented by `start`, `end` and `RRule`. Let's see an example event.
 
 ```typescript
 import { RRule } from 'rrule'
-import { CalendarEvent } from 'rrule-contrib'
+import { CalendarEvent } from 'rrule-duration'
 
 const event = new CalendarEvent({
   start: {
     hour: 10,
     minute: 0,
+    tz: 'UTC',
   },
   end: {
-    hour: 13,
+    hour: 22,
     minute: 30,
+    tz: 'Asia/Tokyo',
   },
   recurrences: [
     new RRule({
@@ -72,6 +72,10 @@ It will return the following array:
 ],
 ```
 
+Note it includes start and end in plain `Date` type.
+
+# Natural Language
+
 You can also get event text as natural language (currently only in English) text.
 
 ```typescript
@@ -79,7 +83,7 @@ event.toText()
 // => 10:00 AM to 13:30 AM every day on Monday, Friday and every month on the 25th
 ```
 
-**Time zone support**
+# Time Zone Support
 
 The most powerful feature of `CalendarEvent` is strong time zone support. We, Remotehour, provides our service globally so this feature has been developed. In the above example, you can pass a `tz` option to `toText` method.
 
diff --git a/package.json b/package.json
index 93a79c4..02a8f8b 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
-  "name": "rrule-contrib",
-  "version": "0.0.4",
-  "description": "RRule related utilities with timezone NLP support",
+  "name": "rrule-duration",
+  "version": "0.0.5",
+  "description": "RRule related utility with timezone NLP support",
   "repository": "git@github.com:remotehour/rrule-duration",
   "author": "gosho-kazuya <kay@remotehour.com>",
   "license": "MIT",
diff --git a/src/CalendarEvent.test.ts b/src/CalendarEvent.test.ts
index 402c94f..ae297f1 100644
--- a/src/CalendarEvent.test.ts
+++ b/src/CalendarEvent.test.ts
@@ -46,6 +46,44 @@ test('CalendarEvent - init with hour and minute, occurences', (t) => {
   )
 })
 
+test('CalendarEvent - different time zone between start and end', (t) => {
+  const event = new CalendarEvent({
+    start: {
+      hour: 10,
+      minute: 0,
+      tz: 'UTC',
+    },
+    end: {
+      hour: 19,
+      minute: 30,
+      tz: 'Asia/Tokyo',
+    },
+    recurrences: [
+      new RRule({
+        freq: RRule.MONTHLY,
+        dtstart: new Date('2020-09-27T09:08:24.000Z'),
+        bymonthday: [],
+        byweekday: [RRule.FR.nth(3)],
+      }),
+    ],
+  })
+
+  t.is(event.toText(), '10:00 AM to 10:30 AM every month on the 3rd Friday')
+
+  MockDate.set(SUMMER)
+  t.deepEqual(
+    event.occurences({
+      between: [new Date('2020-05-01T00:00:00'), new Date('2020-12-31T00:00:00')],
+    }),
+    // FIXME: is it broken?
+    [
+      [new Date('2020-10-16T10:00:00Z'), new Date('2020-10-16T10:30:00Z')],
+      [new Date('2020-11-20T10:00:00Z'), new Date('2020-11-20T10:30:00Z')],
+      [new Date('2020-12-18T10:00:00Z'), new Date('2020-12-18T10:30:00Z')],
+    ],
+  )
+})
+
 test('CalendarEvent - toText format & time zone', (t) => {
   const event = new CalendarEvent({
     start: {
diff --git a/src/CalendarEvent.ts b/src/CalendarEvent.ts
index ad09771..eab9a02 100644
--- a/src/CalendarEvent.ts
+++ b/src/CalendarEvent.ts
@@ -40,10 +40,27 @@ function validateCalendarEventDef(e: CalendarEventDef, name: string) {
   }
 }
 
-function hasMinuteHour(e: CalendarEventDef): e is { hour: number; minute: number } {
+function hasMinuteHour(e: CalendarEventDef): e is { hour: number; minute: number; tz?: string } {
   return Number.isInteger(e.hour) && Number.isInteger(e.minute)
 }
 
+// TODO: Better implementation?
+function getOffsetFromTimeZone(d: dayjs.Dayjs) {
+  try {
+    const diffString = d.format('Z')
+    if (!diffString.includes('+')) {
+      return 0
+    }
+    const [hour, minute] = diffString
+      .replace('+', '')
+      .split(':')
+      .map((x) => parseInt(x))
+    return -1 * (hour * 60 + minute)
+  } catch {
+    return 0
+  }
+}
+
 export class CalendarEvent {
   private start: dayjs.Dayjs
   private end: dayjs.Dayjs
@@ -74,6 +91,7 @@ export class CalendarEvent {
         .utc(date)
         .hour(this.start.hour())
         .minute(this.start.minute())
+        .add(getOffsetFromTimeZone(this.start), 'minute')
         .second(0)
         .millisecond(0)
         .toDate()
@@ -81,6 +99,7 @@ export class CalendarEvent {
         .utc(date)
         .hour(this.end.hour())
         .minute(this.end.minute())
+        .add(getOffsetFromTimeZone(this.end), 'minute')
         .second(0)
         .millisecond(0)
         .toDate()