Well it was pretty obvious when Kento uttered Calibur's identity in Episode 3, but it was never clearly mentioned that Kamen Rider Calibur was his father. But now TV-Asahi in their Episode Guide for Chapter 5 had clearly spoiled the identity.
Seriously, they could have extended it a bit. But now we have another mystery. Who is voicing Kamen Rider Calibur?
Now Starting off with the Episode Guide.
Kamen Rider Saber Chapter 5: "About my friend, the Swordsman of Thunder"
Air Date - October 4
Swordsman of Evil → Kamen Rider Calibur had finally appeared. He is the one who had betrayed Sword of Logos and also ended up involving Touma Kamiyama (Kamen Rider Saber) in the Incident.
With the appearance of Kamen Rider Calibur, the Swordsman stand ready to fight against the threat.
Touma gives his Kaen-Ken Rekka to Swordsmith Tetsuo Daishinji for it's maintenance.
Meanwhile Kento Fukamiya (Kamen Rider Espada) is in a deep thought about something alone. Touma worries about him and also the problems of others.
Kamen Rider Calibur was actually the father of Kento. Kento was thinking of doing something himself to stop his father.
But Ryo Ogami (Kamen Rider Buster) advises him saying it's the problem of the organization.
Zous begins working on his plan to create a new Megido. A new Incident takes place.
Touma proceeds to the location. Kamen Rider Calibur also appears there. Kento rages up.
Kamen Rider Saber Dragon-Eagle is going to Debut in this episode.
The new Megido who is going to appear might be Piranha Megido
Kamen Rider Espada will ride Ride Gatriker
Screenplay - Takuro Fukuda
Director - Kazuya Kamihoriuchi
Action Director - Jun Watanabe from Japan Action Enterprise
Special Effects Director - Hiroshi Butsuda from Tokusatsu Institute