Subject, verb, object of verb (if there is an object)

Joric kicked the ball.

The subject of the sentence is Joric. The ball is the object. This is in the ACTIVE VOICE because of this order.

Here’s how to change the sentence to the PASSIVE VOICE.

The ball was kicked by Joric.

Now the subject of the sentence is the object.

Note: you can only change a sentence to the passive voice when the verb can take an object, in other words, a TRANSITIVE verb.

He is friendly CANNOT be made into a passive voice sentence. FRIENDLY is not an object. IS cannot pass on an action.

In your sentences:

The story of Japan is told by many writers. This is PASSIVE. WHENEVER you see a verb, followed by BY, you’re looking at a PASSIVE construction. To make it ACTIVE, put the force doing the action before the verb and make it the subject of the sentence.

Many writers tell the story of Japan

Active Voice

In sentences written in active voice, the subject performs the action expressed in the verb;

e.g the dog bit the boy (dog is the subject)

Passive Voice

In sentences written in passive voice, the subject receives the action expressed in the verb; the subject is acted upon. The agent performing the action may appear in a “by the . . .” phrase or may be omitted.

e.g. the boy was bitten by the dog.

Verbs are said to be either active (The executive committee approved the new policy) or passive (The new policy was approved by the executive committee) in voice. In the active voice, the subject and verb relationship is straightforward: the subject is a be-er or a do-er and the verb moves the sentence along. In the passive voice, the subject of the sentence is neither a do-er or a be-er, but is acted upon by some other agent or by something unnamed (The new policy was approved).

So in your example active would be:

Many writers tell the story of Japan

Passive:

The story of Japan is told by many writers.

(passive because it’s something that’s happening to the subject not being done by it!)

Active voice is when you say Writers told the story of Japan

Andy broke the pen (the action is Andy breaking the pen)

Passive voice is someone saying about the action:

The pen was broken by Andy