Counterattack System appeared when I'm already At The Mahayana Realm - Chapter 639 - 638: Retreat at Every Turn

Throughout this current life of mine, I will pay no attention to my past lives, nor will I seek future lives. I wish to live vigorously, to pay back debt of gratitude and fulfill duty to avenge, to defeat valiant heroes from all species, and to proudly laugh at all the Gods and Demons of the Six Path of Reincarnation!

- Description from Novelupdates

Seeing the cause of justice, the student Ning Tianlin, who was strangled, accidentally gained a combat system in the local government and returned to Yang.

What the hell, your fighting power is only fifty, then you still pretend to be me! I’m sorry to tell you 10,000 points of combat power!

What are you doing, have you been boiled down, trained in martial arts, and practiced iron gear? The fighting power is five hundred? That has something to do with me, I won’t tell you, the clothes I wear, but combat equipment! Just a single underwear, can add a thousand fighting power to me!

Hey, why do you say my combat power has increased so fast? Can I tell you that if I step on an ant and destroy a cockroach, can I increase my combat effectiveness?

- Description from uukanshu

Talented in Magecraft but useless in physical combat?

Once through the pirates, Lu En became the son of Monkey d Dragon, a grandfather named Monkey d Karp, and an unreliable and neurotic younger brother named Luffy.

Fortunately, the ghost back system is activated!

The completion of the ghost back is 10%, and the training effect is increased by 100 times!

The completion of the ghost back is 20%, and the training effect is increased by 1000 times!

…

One day, Lu En, a ghost-backed master, appeared in front of Luffy who was shouting to go to sea, and made Luffy cry on the spot.

Luffy: “The pirates in the sea are all monsters like my brother? I don’t want to go out to sea!”

Garp: “For a long time, the two boys, Long and Luffy, with small arms and calves, I really doubt that they are not my sons and grandsons. Like Lu En, they are the grandsons of the old man!”

Warring States: “The strongest creature in the sea, land and air is Kaido? No, it’s Lu En!”

- Description from novelbuddy