Megastar Amitabh Bachchan says he is relishing the "lovely" phase of being able to spend time with his grandchildren.

Bachchan, who has three grandchildren — Aaradhya, Navya Naveli and Agstya, will be seen playing a superhero in the upcoming animated TV series Astra Force.

"When you are 73 these are the kind of people you meet… You meet kids, they are the happiest persons. We pass the age of youth, study, university, girls, marriage, wife, children… Now is the age of grandchildren," Bachchan told PTI.

"It is a lovely phase, a lot of people say the best phase of an individual’s life is when he spends time with grandchildren. I will endorse that… Therefore this (playing superhero ‘Astra’) fitted into my mind…," he added.

In Astra Force, the Piku star plays a grandfather with great powers and strength.

"There are two children (in the show) who are twins and they are like my grandchildren. I love being in their company," he said.

Aaradhya has yet not seen the picture of his grandfather as an animated hero.

"She has not seen yet… It is too early to show her," he said.

Bachchan revealed that Aaradhya has her set of favourite cartoons, but he is not aware about them.

"I don’t know (about her favourite cartoon) as she goes so rapidly on IPad watching them that it is difficult to catch up. But it (superhero ‘Astra’ to be played by him) will be a great incentive for her to have her lunch, dinner, breakfast, because unless she sees something on television she won’t eat anything," he said.

"It is becoming a universal practice with all kids.

She likes to see all these cartoons and hopefully we will come soon with it ("Astra Force" series)," he said.

Whenever Aaradhya sees her grandfather on the big screen, she is happy about it.

"She sees visuals sometimes. She is happy about it. I remember when I was a kid, I used to see SupermanBatman.

I feel some things you imbibe they remain with you throughout your life," the veteran actor said. .

As a doting grandfather, Bachchan tells stories of Mahabharat and Ramayan to Aaradhya making her aware of that side of the world as well.

"We do narrate her certain things. I will narrate her ‘Astra’ stories also," he said.

When Bachchan was offered the role to play the superhero in Astra Force, he first thought the makers were not serious about it.

"When they came to me first, I thought they were joking.

They came up with a lot of research and it was very impressive work that they had done.

"So, it was not difficult to give consent to it. Soon after the initial meetings, I felt this is something the entertainment industry in India has not been able to put together in an impressive manner as it should be done," Bachchan said.

The actor even gave inputs for his look in the animated series.

"They came to me with a design and I felt it would be wrong for them to put me in a younger mode, because I am no longer young. So, the first thing we agreed upon was that it (the superhero) has to be how I look like now," he said.

"Somebody who not only has power, strength of a superhero, but he has to have the mind of somebody who is wise. In real life there is always an elder who gives advice," he said, without divulging much about his role.

Astra Force, a funny and fast paced action-adventure series, which will go on air in early 2017 on Disney Channel India.