Sun Stone
Lost energy
First of all, Since the dawn of history, mankind has been using Sun Stone as energy. It is the time when the Kingdom of Zeal was just founded. By using Sun Stone energy, the Kingdom of Zeal floated the continent, controlled the environment, advanced magic and technology.
However, in the era of Queen Zeal, the Kingdom of Zeal was to use Lavos' huge energy. Therefore, Queen Zeal sealed the outdated Sun Stone. The sealed Sun Stone was kept in the southern Continent of the Kingdom. Crono can not go because this South continent was isolated from the continent with the Zeal Palace.
This Sun Stone is one of the energies that could compete with Lavos energy in history. To fight Lavos, it must be the energy that Crono should get.
How to get
2300 A.D. Sun Shrine
In 2300 A.D., the Sun Temple appears on the ground for the first time in 14300 years due to crustal deformation after "Lavos Day". First, destroy San of Sun, and get a "Dark Stone" that had been sealed during the even 14300 years.
65000000 B.C. Sun Shrine
Let's look at the world map. During the period from the Prehistory to the Future, there is a place that is far appeared on the ground. In the northeast of the world map, there is "the Sun Shrine" with the most stable sunlight. Let's set Dark Stone there.
2300 A.D. Sun Shrine
The Sun Stone takes time anyway to regain energy. However, the Sun Stone should be in the future is gone. Since it can not be thought that someone took it in 2300 A.D., let's return to 1000 A.D..
1000 A.D. Mayor's Manor (Porre)
Crono asks the mayor to give up the Moon Stone, but he will never give over.
600 A.D. Mayor's Manor (Porre Village)
(It's pretty simple as in the story of Chrono Trigger.) Here, Crono can easily change history. First, in the Mayor's Manor in the Porre Village, a women is in trouble that she run out of "Spiced Jerky".
1000 A.D. Snail Stop (Porre)
Let's buy "Spiced Jerky" which is sold at "Snail Stop".
600 A.D. the Mayor's Manor (Porre Village)
Talk to the woman again and give "Spiced Jerky" for free.
1000 A.D. Mayor's Manor (Porre)
Because of helping the town mayor's ancestor, the character of the mayor changed. Therefore, the town mayor is willing to give Moon Stone to Chrono. Let's set the dark stone regained in the contemporary "Lust of the Sun".
2300 A.D. Sun Shrine
Finally the Moon Stone has regained its radiance and turned into a "Sun Stone". Take this.
1000 A.D. Lucca's House
Wondershot and Sunglasses can be a get. In addition, it satisfies the condition to get the Rainbow .