Hello Summoner! :D
I see that you've come looking for a build for the human Beyblade Garen! Well
I surely Hope this build is what your hoping for. I've played with it, and it is still
in the process of being made better in a slow agonizing process of PvP Yolo Que, but this is the build I've come up with so Far.

P.S. Be sure to check the indicators next to the items and such for explanations!

First this is first. Items.

A friendly Reminder, This build is still under construction, and is more than less likely, to be update, but as of right now, this is the best combination I have managed to match up.

There is an explanation for each item in the indicators, but here, I will go more in depth with each item and why I choose them.(Its not really important that you do check those out, but id prefer it)

[*] Starter Items:
The reasoning behind this is really common knowledge, but for the newer people, I'll explain I guess. 3 Potions is the most you should get at the begging of each game really. And the boots are for speed which is kind of obvious, BUT they are very necessary, so don't just say you don't need them.

[*] Brutal:
As explained in the Indicators, an early The Brutalizer on Garen is a very good idea, and this added with the fact that it builds into future items makes it perfect.

[*] Dat Health:
In this part of the item build, Giant's Belt is also used to build into future items. While as it can be difficult to gather that much money this early in game, last hit everything you can. at this point, it's kill or be killed because this item is absolutely needed early game. This item doesn't come before The Brutalizer however because the The Brutalizer will make it a little easier to get this much gold. It's needed because of the health it provides early game to about mid game is invaluable. And it builds up into future items. So, Like i stated, Its "No Holds Bards" when you are trying to get this item. But, as a friendly reminder, play it safe. You don't want to go off feed them and lose.

[*] Boots:
There are 3 boots here to choose from. Boots of Swiftness, Ionian Boots of Lucidity, and Sorcerer's Shoes. This is why I said its necessary that you get boots at start by the way.All these three things are not meant to be bought!!! I know someone out there is probably like, "Huh? what? Why all three?", But no, you buy 1! However, which one you buy completely depends on the game you are in. So now that that is out of the way, we can get to the reasoning.
The Boots of Swiftness are to be chosen if the enemy team is high on Crowd control effects that your Q and flash just can't seem to get you out off, or just a lot of them.
The Ionian Boots of Lucidity are meant for the little extra CD reduction, but I do NOT recommend them unless somehow ahead and fed already and even still, I would not recommend them full heartedly. But! if you find it would be a needed, then by all means, buy it! Don't let a simple build restrict you.
The Sorcerer's Shoes is for when u get you Drop your ult. Your Ult also secretly does Magical Damage, which is why I Like this item.
Out of them all, I recommend Boots of Swiftness, overall, it saves your flashes and Q's that are necessary for combos.

[*] Dat Damage:
The item Black Cleaver I choose because of it is overall great for Garen with its mixture of AD, CD, extra health, and Armour Penetration, it just makes it great for an up close and personal character like Garen. However, like stated in the indicator, it really depends on how well your game is going. I secondarily recommend Bloodthirster for its extra AD per kill and its life steal. There is also a third option of Ravenous Hydra,but seeing how with the next item, AOE becomes your middle name, this item nearly becomes kind of inferior because you'r more than less likely using your Judgment more than your Auto attack. BUT!!!!!! Do not ignore the possibility of the Hydra. With it's extra Damage, AOE, and life steal it can be deadly. If your CD is up, and it looks like your about to go in a team fight, then you will have a back up till you can drop an ability. Like always though, its your call in how well the game is going and the enemy team.

[*] Taste The Sun:
This item is like Garen's Childhood Blanky. He should never go anywhere without his Sunfire Aegis. It was like, made for Garen. With its constant AOE damaging mixed with you Judgment it's basically game over for all in range of your spin. however, be careful when near enemy towers. with this blanket it harms everyone in range, meaning even if your not trying to attack an enemy champ, your cape will, thus making the tower attack you, leaving you very vulnerable as the tower takes a nice chunk from your health.

[*] Defense Time:
This item is also based on how the game is(Don't you just hate that?). Meaning if its going downhill, then use this, and if its good, then use this. But in this case, it's not up to that. It is completely up to how the enemy team is. If they are focused on Damage and AD, its all about that Thornmail. With that Defense, you can just laugh at a bunch of their champs, but it doesn't have the great passives like the Spirit Visage. If they are focused on magic and AP then you should get the Spirit Visage not only a great item for Garen, it also has a dash of magic resistance, making it that much harder to kill. If your feeling lucky and that your team can back you up no matter what team they are against, and their AD is kind of low, then I would always recommend the Spirit Visage for Garen. It's just an overall good item for him.

[*] Completely Optional:
Like it states, this item is completely optional, among any others you want. At this point in the game, your either winning or loosing, and either way it is OK to go with any of these items. The Infinity Edge is for that extra damage and crit chance and damage in spin and hit, and I recommend against any type of champ in a winning or loosing situation. Maw of Malmortius I recommend if those Pesky mana running AP characters are still picking on you. with its extra damage and astounding AD, how could I not? lastly was an odd one however. Rabadon's Deathcap I recommend ONLY if your are WINNING. This item is known to piss off people because when Garen drops dat ult... Demacian Justice lets just say, everyone needs a change of underpants.

Next up is Runes!

The runes on Garen are not hard at all. Just throw together A LOT of AD, and mix in Cool down reduction where you can, and you will be set....Garen....Just as easy as he appears Ladies and Gentalmen

Good old Maseries

Basically the same concept as your Runes. If you focus on AD first, and get that tree up first, you can go far with Garen. Just like I said with runes, just throw in CD reduction. The rest is kinda self explanatory.

Main Combo

This combo works well all the way through the game for securing kills or just flat ashe (see what i did there? <.<) killing someone. It goes like:

Flash+ Decisive Strike+ Judgment+ Ignite+ Demacian Justice

To break be honest, don't waist your ignite or flash if you can get away with it. You should save these these till you ABSOLUTLY need them. in fact, you should only use ignite if you can't chase any further or you aren't doing as much damage as you hoped. you should activate this when you are hitting the enemy with your Judgment. and lastly, if you know for a fact that he is going to get away, Bring down God's Wraith upon him for being so fast and built with Demacian Justice. That ought to cut him down to size. That size being ash. If that fails. Then well. Their's nothing you can do but keep building and take the heat from your team about missing the kill.

Thank you!

[*] Thank you for reading my build, and taking note of what i have said. Please remember that this build is still being worked on, so if you find something that works better, feel free to tell me.

[*] on a final note, this is also my first Build I've posted, sooo... that could explain the lack of professionalism if you where looking for that here.

[*] So on that note, I thank you again! And I Wish you all Fine Bloodshed on The Fields of Justice.