If you want to know why is Goku Pure Hearted, we have to dig deep and go back to the creator of Dragon Ball himself, Toriyama.
Toriyama himself from the special exhibit, The world of Akira Toriyama from 2015 where Toriyama and Nozawa both spoke about Son Goku.
Toriyama said this about Son Goku and I quote “I wanted him to have the sense of being a rare person who only seeks to become stronger than before. So strong that it feels like there’s no one as pure as this person and someone who saves everyone. As a result of that, he himself at least has a very pure sincerity about wanting to become stronger.” end quote.

What I depict the most from that interview was the fact that Goku is a good guy at all times in Drago Ball.
Although Goku did a lot of good things in Dragon Ball as a result base on Toriyama’s views.
When you examine the manga and the original sort of the idea behind pure hearted Goku or pure-heartedness, it takes a bit of a turn.
This turn also provides a much more complex review of Toriyama’s upbringing as somebody in the Eastern world who is familiar with various philosophies of the past.
Why is Goku Pure Hearted?
Goku is pure heated because he has no desires or need or selfishness in life and because he detaches himself from world wild virtues.
When it comes to having a purity of heart it does not necessarily mean that they are a perfect person or that they are free from having somewhat of a sinful nature.
Nor does it hinder them from doing things that are bad. Obviously, when it comes to the character of Goku he has committed a murder at the end of the DBZ series.
Goku definitely killed Majin Buu and he killed several members of the Red Ribbon Army as well in Dragon Ball.
Also, if you count the Dragon Ball Z movies and Dragon Ball GT, Goku has a bigger body count there.
Goku even tried to kill Frieza on Namek because when that last blow hits Frieza, it was meant to take him out for good.
However, It didn’t kill Frieza. We are meant to think that it did but obviously when Goku kills in Dragon Ball it’s meant to be seen more so as a last resort.
Or more so as something to where he had to do it because the person he killed was exceptionally involved in some anus act.
So killing these characters is a necessity to protect the Earth and in some ways, the universe from more people dying.
Related Read: How old is Goku?
Goku Being Pure Hearted
This whole thing about Goku being pure at heart is something that came up time and time again.
However, it started all the way back in early Dragon Ball when Goku was able to ride the King Tone Cloud otherwise known as the nimbus cloud.
This cloud belongs to Master Roshi and to ride the cloud you have to have a pure heart.
As we’ve discussed in the past, Toriyama is notorious for using some ancient Asian Buddhist mythology and philosophy in Dragon Ball stories.
Also, another example is in Dr. Slump and the idea of having a pure heart is no different.
When you really look into all the mythology in Dragon Ball and the metaphors that Toriyama gives us.
You would really pick up on the fact that there’s a lot of secret messages in Dragon Ball that Toriyama’s convince us that most of us never pick up on.
Why?
Well, because we’re too caught up in the action and The comedy of the series. However, make no mistake, Toriyama, when he was younger, had an incredible sense of history.
He and an incredible sense of ancient history, he was a total genius and well knowledgeable with stuff like this.
They believe that having a pure heart is tied to the innocence of your soul in Japanese.
It’s called Shiraki the Art of the uncarved log. The reason why they call it the uncarved log is that its some sort of a metaphor.
It really meant that a piece of wood in nature that has yet to be cut down by a human.
Japanese Ancient Meaning Of Pure Hearted
So what does the Japanese Shiraki mean by ”Cut down by man?” Well, to keep it’s the idea of that nature and the way nature creates your true self.
In other words, when you’re a child you have no real negativity inside you, you are born innocent in nature.
This is something that is pure and uncorrupted. Not like those who are having trials and tribulations that make them have negative thoughts and do bad things.
So we are all born good, however, later on, we turn out bad. That is the ultimate opposite of being pure hearted.
How To Become a Pure Hearted Person like Goku?
The goal is to go back and discover our former true self, our true pure hearted Goku version of who we were when we were born.
Life experiences mold us and shape us into the person we become. But through meditation self-cultivation and mental training, you can return back to the person who you originally were.
The only way to achieve this is by letting go of our desires our needs and our selfishness and detach ourselves from world wild virtue.
Goku is a simple pure hearted person who was raised in nature by his grandpa and that has no attachment to anything but is Grandpa Gohan.
Nonetheless, the first few arcs of Dragon Ball are a motivating factor for the character. But even as Toriyama tells the story of Dragon Ball and the life of Goku.
It unraveled that Goku is still Incorruptible. Goku never went evil and even though he didn’t do very selfish things, he still was inherently a good person.
Remember just because you’re trying to achieve perfection or virtuousness is not mean that you’re going to not slip up a few times.
Nonetheless, if we take one particular character in Dragon Ball Goku’s best friend Krillin who when we first meet him he can’t even ride the Nimbus Cloud.
Krillin could not ride Nimbus Cloud because he’s not pure of heart.
He has lustful thought but later in the series during the battle with Vegeta on Earth.
Krillin was able to successfully utilize Goku’s Genkidama and it was said that the Genkidama can only be used by somebody who has a pure heart.
Conclusion
So the idea is that at some point in your life you may not have a pure heart but you can attain it.
That seems to be what happened here with Krillin Goku’s best friend. Now speaking Vegeta is the perfect example of somebody like this early in the series.
That was the whole life of Vegeta since he met Goku and the Z fighters. Let’s keep it real, Vegeta is a very insecure person and a very flawed person.
However, he has redeemed himself many times throughout the Dragon Ball series. Even though he still has a grudge against Goku it’s not evil intentions.
So we could also say being pure hearted Goku is like bing virgin who has not undergo any sexual intercourse. This like the quote “A tree that has not been toughed my human in nature.”
I hope this in for providing the answer you are looking for about Goku and why he so pure heated.
If you have any questions or want to reach out to me hit me up in the contact box.