"I can now tell my father that all was not for nothing," he said.
The graphic novel follows Antonio senior through the bloody 1936-9 civil war, General Francisco Franco's subsequent dictatorship and the fragile transition to democracy after his death in 1975.
At the time, authorities opted to draw a veil over the past, and this dark period of Spain's history remains suppressed to this day, for fear of reviving once-bloody divisions, despite growing calls to heal still-open wounds.
- Raw, graphic -
But fiction has attempted to plug this hole and the theme of the war has abounded in films, novels... and in comic books.
Michel Matly, who has published a thesis on the conflict's portrayal in comics at France's Blaise Pascal University, says the format comic-book format has a long history.
Both sides of the civil war -- Republicans and Nationalists -- used comics for propaganda.
"This was a time when people sometimes had trouble reading or were illiterate, and comics were a good way to relay messages," he says.
But under Franco's dictatorship the theme was largely stifled.
It was only in the early days of democracy that it came back to life in comic books, albeit in watered-down mode in keeping with the general policy of appeasement.
Then in the 1990s, the industry went through a crisis during which many comic magazines shut down, Matly says.
At the turn of the century, the industry took off again, fuelled by an economic bonanza and the arrival of graphic novels -- a longer book format.
At the same time, more and more people were clamouring for the civil war to be addressed -- culminating in a 2007 "historical memory law" that finally recognised victims of the conflict and Franco's dictatorship.
"People talked more about the issue... many books were written, and the same thing happened in comics," says Paco Roca, who created several acclaimed graphic novels on the conflict.
This time round, though, the comic books were more raw.
Carlos Gimenez's "36-39 Malos Tiempos" ("36-39 Bad Times") about the siege of Madrid by nationalist forces is a case in point.
Based on the testimony of a man who experienced the war, it graphically recounts harrowing stories: from a mother's decision to give away her son's beloved cat, to a starving neighbour or a man's terror at seeing someone decapitated in a bombing.
- 'Way to testify' -
But whereas people reached saturation point with books and films on the issue, graphic novels continued to appeal with their powerful, accessible mix of text and drawings, even if the industry remains small.
Matly says that more than 120 comics were published between 2001 and 2015 in Spain on the subject, and they keep coming.
Historian Paul Preston's definitive book on the conflict for instance has been adapted into a graphic novel this year.
Sarah Harris, a US specialist in narratives of trauma in Spanish fiction, says that the nature of comics -- where people can pause and reflect on a page -- makes them a powerful medium for remembrance.
"It's become a way to testify," Altarriba says.
"I speak a lot with readers who are the great-grandchildren of people who experienced the war... and it's clear that there is a strong will to fill the gaps."
Roca experienced this first hand when he created "Los Surcos del Azar" ("Furrows of Fate") about Miguel Campos, who fled the war to north Africa and went on to fight the Nazis in France.
Campos genuinely existed although he disappeared in France, prompting Roca to fictionalise the latter part of the story.
But Campos's granddaughter read it and contacted Roca, thinking he may have traced him down.
"I had to say it was fiction... But I put the family in touch with the historian Robert Coale and they are now piecing together his life."
Summing up the malaise surrounding the civil war, late author Ramiro Pinilla wrote in a forward to Gimenez's "36-39 Malos Tiempos" that Spain wanted nothing more than to put the past behind.
"We want to turn the page... but not before reading it," he said.
"Because there was a war, I saw it."