Black Iron's Glory - Chapter 499 - Conversation on the Train

Forge unparalleled mechs with the ambition of old age, and use the galaxy as a knife to smash the edge of the empire.

His name is Ji Xinghe. When he was 65 years old, he went to Alien Battlefield to avenge his son.

The old man is standing on the ground, his ambition is a thousand miles away, the old man wears armor, and fights to the galaxy, the old man drags his sword, it is not for glory.

- Description from novelbuddy

One day I got a younger sister.Only I know her true identity.

At 20 years old, Su He married Mr. Jiang, a business tycoon with billions to his name, proudly hailed as a business mogul. Upon learning of this, people said that she, a country bumpkin lacking background and wealth, was merely a poor doctor with a beautiful appearance, unworthy of the esteemed Jiang family head. Gradually, however, people discovered that this 'poor doctor' with 'no background' was in fact the jewel of a prestigious medical family in the capital, an expert surgeon in the medical field, an heir to a medical research institute, and a mysterious designer... Everyone knew that within Mr. Jiang's heart, there was a cherished figure. As the four-year marriage agreement neared its end, the man handed her a document, his tone gentle yet assertive: 'Sign it!' 'A divorce agreement?' Su He asked, her eyes bright with unconcealed excitement and anticipation, having longed for a divorce. The man snorted coldly, 'Just sign it!' Not long after, Mr. Jiang reneged, stating: 'Since you've given birth to my child, you'll be mine for life!'

Crossing to One Piece world, he became Roger’s younger brother.