Moshi Role Playing Game no Sekai ni SNS ga Attara

In a fantasy world where smartphones and the internet exist, the Hero has become a total shut-in, refusing to socialize with anyone. However, his world gets a little larger when he meets the Demon Lord online. The two hit it off, and the Hero decides he wants to meet her in person. The outside world is a dangerous place, though, and the shy young man only has 1 HP...This story is an adventure romance for the digital age told almost entirely through chat logs!

(Source: Yen Press)