A bus tour from Delhi to Manali, Keylong, Leh, and Ladakh is an adventurous journey covering a significant part of the Indian Himalayas. Here's a suggested itinerary for such a tour:

Day 1: Delhi to Manali

Depart from Delhi in the evening by bus to Manali, a journey of approximately 550 kilometers, taking around 12-14 hours.
Overnight journey to Manali.
Day 2: Arrival in Manali

Arrive in Manali in the morning.
Check into your hotel and relax.
Spend the day exploring local attractions like Hadimba Devi Temple, Manu Temple, Vashisht Village, and the Mall Road.
Overnight stay in Manali.
Day 3: Manali to Keylong

Depart from Manali to Keylong by bus, a journey of around 115 kilometers, taking approximately 5-6 hours.
En route, enjoy the scenic beauty of Rohtang Pass and Lahaul Valley.
Arrive in Keylong and check into your accommodation.
Explore the surroundings and relax.
Overnight stay in Keylong.
Day 4: Keylong to Leh

Depart from Keylong to Leh by bus, covering a distance of approximately 350 kilometers, taking around 12-14 hours.
Enjoy breathtaking views of the Himalayas and the high-altitude passes like Baralacha La and Tanglang La.
Arrive in Leh and check into your hotel.
Rest and acclimatize to the high altitude.
Overnight stay in Leh.
Day 5-6: Leh Sightseeing

Spend these days exploring Leh and its nearby attractions.
Visit places like Leh Palace, Shanti Stupa, Hall of Fame, Magnetic Hill, Gurudwara Pathar Sahib, and the confluence of the Indus and Zanskar rivers.
Explore the local markets and indulge in Ladakhi cuisine.
Overnight stays in Leh.
Day 7: Leh to Ladakh (Nubra Valley)

Depart from Leh to Nubra Valley by bus, crossing the famous Khardung La Pass, one of the highest motorable passes in the world.
Explore Diskit Monastery, Hunder Sand Dunes, and enjoy a camel safari (optional).
Overnight stay in Nubra Valley.
Day 8: Ladakh (Nubra Valley) to Leh

After breakfast, return to Leh from Nubra Valley by bus.
En route, visit the picturesque villages of Sumur and Panamik known for hot springs.
Arrive back in Leh by evening.
Overnight stay in Leh.
Day 9: Leh to Delhi

Depart from Leh to Delhi by bus, marking the end of your adventurous journey.
Overnight journey to Delhi.
Day 10: Arrival in Delhi

Arrive in Delhi in the morning.
Tour concludes.
This itinerary offers a comprehensive experience of the diverse landscapes, culture, and adventure opportunities in the Himalayan region, from the lush greenery of Manali to the stark beauty of Ladakh. Make sure to consider acclimatization and weather conditions, especially when traveling to high-altitude regions like Leh and Ladakh.