In the Church of Alexandra and Antonina lies a coffin. It is draped with a Russian tricolour. Resting on the casket: a service cap and a photograph.
Mikhail Orchikov was deputy commander of a motor-rifle brigade. He was killed in action in Ukraine. Armed Russian soldiers form a guard of honour.
An Orthodox priest walks around the casket reciting prayers and swinging an ornate metal vessel emitting burning incense. The pungent scent fills the chapel, mixing with the sweet cadences of the church choir. The dead soldier's widow, head covered in a black scarf, is being comforted by relatives.
How many Russian servicemen have been killed in Ukraine? It is a criminal offence in Russia to report anything other than the official figures.
According to information released by Russia's Defence Ministry, 498 soldiers have lost their lives in what the Kremlin calls its "special military operation". Those are the latest figures, from 2 March. There has been no update for two weeks.
"The situation in our country isn't simple," the priest tells the congregation. "Everyone understands that."
The Kremlin wants the public to believe that the Russian soldiers in Ukraine are heroes and that Russia's offensive there is an act of self-defence.
In a recent edition of state TV's flagship weekly news show, the anchor claimed that if Russia "hadn't intervened now, in three years' time Ukraine would have been in Nato… with a nuclear bomb. [Ukraine] would definitely advance on Crimea, then on southern Russia." An alternative reality, in which Ukraine is the aggressor.
On the streets of Kostroma, many appear to believe the official Kremlin line.
That's partly due to the power of television in shaping public opinion. But also, at moments of crisis, many Russians instinctively rally around its leader - as if they don't want to believe that their president may have made the wrong decision.
"Nato wants to set up shop right next to us [in Ukraine] and they've got nuclear weapons," Nikolai tells me. "Well done Putin. He didn't let them."
"Russia needs to push on till the end," declares pensioner Nina Ivanovna.
"How much do you trust the information you're getting on Russian TV about this?" I ask her. "I trust it. Why shouldn't I? It's the internet I don't trust."
"I don't know," she replies.
Not everyone supports Russia's offensive in Ukraine. In the village of Nikolskoye, I visit the home of Orthodox priest, Father Ioann Burdin. He recently delivered an anti-war sermon and voiced his criticism on the church website.
He was later detained and fined under a new law for discrediting the Russian Armed Forces.
"I believe that any bloodshed, whatever the cause and however you try to justify it, is still a sin," Father Ioann tells me. "Blood is on the hands of the person who spilled it. If an order was given, it's on the hands of whoever gave the order, supported it or stayed silent."
"The worst thing of all is that hatred has appeared. It will grow deeper and deeper, because we can see that the situation [with Ukraine] isn't ending. There is no political will to stop this. Hatred on both sides will strengthen and become a wall between our peoples for decades to come."
At a cemetery in Kostroma, eight soldiers bear Mikhail's coffin to the grave. A military band plays solemn music. Then a gun salute and, to the Russian national anthem, the casket is lowered into the ground.
There is a brief speech: "The loss of a son, brother, father is always a tragedy, but we are proud that he died defending our people, our children, our country."
In Kostroma, they call Mikhail "a defender of the Fatherland".
And yet it was Russia's army that crossed the border into a sovereign nation and attacked Ukraine on the orders of President Putin. The Kremlin leader claims that the aim of his "special military operation" is to "demilitarise and de-Nazify" Ukraine, as if the Ukrainian government is overrun with fascists - which is simply not true.
In recent days Russian officials have barely concealed their wider objectives. The Russian Foreign Minister Sergei Lavrov has said that what's happening in Ukraine "…is a life-and-death battle for Russia's right to be on the political map of the world with full respect for their legitimate interests".
In other words, this is about geopolitics, and Moscow's determination to force Ukraine back into Russia's sphere of influence.
That's something the government is Ukraine is determined to prevent.