The incident took place at around 4.20pm local time on Saturday.
Raharja was still breathing when his teammates rushed him from the field to safety, according to Indonesia’s PRFM News. At the hospital, he later succumbed.
Raharja was competing in a friendly match between Football Boots Indonesia (FBI) Subang and FC Bandung.
The weather on the day was cloudy, social media users said.
A video of the moment has since been widely shared on social media.
According to The Standard, in 2023 another Indonesian footballer from Bojonegoro, East Java, was struck by lightning during the Soeratin U-13 Cup. He was revived after about 20 minutes.
In March 2004, Jiang Tao, an 18-year-old athlete who played for the now-disbanded Chinese S-League team Sinchi FC, lost his life when lightning struck him during a training session at Jurong Stadium, a venue that has since been torn down.
On its Instagram account, the FBI Subang shared a photo of Septian, accompanied by a caption marking the date of his passing with a rose emoji.
Among the many messages offering condolences, there was one from Cristian Gonzales, the former striker for the Indonesian national team.
Another team under the FBI umbrella, from the regency of Magelang, posted a photograph of its players having a moment of silence in remembrance for Septian, Strait Times reported.