How Was He Chosen by Sewashi Nobi's Great-Grandson and Sent to Nobita's Side

Okay, this is a fantastic question—it's the very starting point of the entire Doraemon story! Let me break it down for you. The whole process is actually full of coincidences and a touch of "fate."

How Doraemon Was Chosen and Sent to Nobita: A "Beautiful" Accident

Simply put, Doraemon wasn't chosen because he was the strongest or most capable robot. Quite the opposite: it was because he was a "defective model" at the time and was "accidentally" bought by Sewashi.

Step 1: Choosing Doraemon – Because He Was Cheap, and Due to a "Slip of the Finger"!

This story starts with Doraemon's "origins."

Doraemon was a "bargain bin" robot Doraemon wasn't considered a qualified product at the 22nd-century robot manufacturing plant (Matsushiba Factory). He had issues right on the production line (a screw was knocked loose by an electric shock), which later caused him to be clumsy and inept at robot school. Even worse, his ears were later bitten off by a robotic mouse. He cried so hard from sadness that his yellow paint washed off, turning him into the familiar blue color we know. So, when he was put up for sale at a robot expo, he was essentially an unwanted, discounted "defective" robot.
Sewashi's "Divine Touch" Nobita's great-great-grandson, Sewashi, wasn't well-off, largely due to the "mess" Nobita had left behind for his descendants. Therefore, Sewashi's family couldn't afford the latest, coolest, highest-performance nanny robots.

At a robot expo, the infant Sewashi, dazzled by the array of robots, completely by accident and unintentionally, pressed Doraemon's purchase button!

And so, because of a baby's "slip of the finger," this blue, earless, somewhat clumsy discount robot was bought by Sewashi's family through a twist of fate.

Although bought by accident, Doraemon and Sewashi developed a very strong bond. Doraemon took care of little Sewashi wholeheartedly. They grew up together, forming a deep friendship.

Step 2: Sending Him to Nobita – To Change a Tragic Future

When Sewashi grew older, seeing his family's straitened circumstances (like only getting 50 yen as New Year's money) and looking through old photo albums, he finally found the root of the problem—his great-great-grandfather (his grandfather's grandfather), Nobi Nobita.

The Original Future: Before Doraemon arrived, Nobita's future was bleak: he would grow up to start a company, only for it to burn down, leaving him deep in debt. He would marry Gian's sister, Jaiko. This debt would then be passed down through generations, resulting in Sewashi's generation living in poverty.
The Plan to Change the Future: Sewashi decided this couldn't go on! He believed that if he could go back in time and help his hopeless great-great-grandfather become more capable and happier, it might change the entire family's destiny. The best outcome would be for Nobita to marry Shizuka Minamoto, whom he always liked. If this goal was achieved, the family's future would take a completely different, happier path.

Step 3: Executing the Plan – How to Send Him? And How to Ensure Success?

With a plan in place, it was time to execute it.

Transportation: Sewashi and Doraemon boarded a time machine and traveled from the 22nd century. They arrived in Nobita's era through the "space-time tunnel entrance" in the drawer of Nobita's desk. This is why Doraemon always emerges from the drawer.
"Insurance Policy": Sewashi was also worried that Doraemon might find the task too difficult or get fed up with Nobita's laziness and try to return to the 22nd century halfway through. To prevent this, he installed an "enforcement program" in Doraemon. This program stipulated: Doraemon could not return to the 22nd century until Nobita achieved happiness.

It was like a one-way ticket: no success, no return home. This also explains why, even though Doraemon often gets so frustrated with Nobita that he jumps with anger and threatens to go back to the future, he ultimately stays and pulls out various gadgets to help him. He was "locked" into this mission.

To Summarize

So, the entire process can be summarized as:

An Accidental Meeting: The infant Sewashi, because his family was poor, could only look at discount robots. He accidentally bought the "defective" Doraemon with a slip of the finger.
A Deep Friendship: Doraemon and Sewashi formed a bond that went beyond master and servant.
Determination to Change Fate: To escape the family's cycle of poverty, Sewashi decided to send his most trusted companion, Doraemon, to help his incompetent great-great-grandfather, Nobita.
A One-Way Journey: Doraemon was sent to the past via time machine, with an "enforcement program" ensuring he couldn't return until the mission succeeded.

Therefore, Doraemon's arrival at Nobita's side is entirely the beginning of a wonderful story woven together by accident, poverty, friendship, and determination!