Kim Seon Ho is not the lead actor in “Start-Up”, tvN’s K-drama about tech startups that is now streaming on Netflix. But he’s definitely stealing the show — and hearts — because of his charming portrayal of Han Jip Yeong. And just as in previous episodes, he’s the MVP of “Start-Up” Episode 4.

What makes this “Start-Up” Episode 4 even more heartwarming is that it celebrates the birthday of Nam Do San. Not the person whose real name is Nam Do San, played by Nam Joo Hyuk. But the “Nam Do San” who wrote the letters to a young Seo Dal Mi (Bae Suzy). The “Nam Do San” who became Dal Mi’s first love. “The Nam Do San in the old days”, as Dal Mi’s grandmother calls him. In other words, the “Good Boy”, Jip Yeong. Spoilers ahead if you haven’t seen the episode.

‘Did you know I have huge hands?’

“Start-Up” Episode 4 shows the relationship between Dal Mi and Do San further developing. In a charming sequence, Dal Mi says that she thought her hands are pretty big, but they look tiny compared to Do San’s hands. And then holds his hand for the rest of the bus ride.

This episode also gives us more insights into the personality of Do San. Including how naive he and his Samsan Tech co-founders are, because they were about to give away their algorithms to a team of developers pretending to be investors, before Jip Yeong arrives to save the day.

Later, in a hilarious series of flashbacks, Do San’s co-founder Lee Chul San (Yoo Su Bin) explains to Jip Yeong how all three of them have never had girlfriends. We see how uncompromising Do San is about being a stickler for logic and science, even driving away a girl because she believes that blood type determines someone’s personality.

We see how stressed Jip Yeong becomes in trying to make sure that Do San can continue fooling Dal Mi and making her happy. And how even he can’t remember the birthday wish he told Dal Mi in his letter, because it was so long ago.

‘What’s ordinary to one person’

The birthday celebration of “Nam Do San” is a strange one, indeed, as Jip Yeong once again gives Samsan Tech his place as their office, and Dal Mi makes “Nam Do San”‘s birthday wish from long ago come true.

It was while Dal Mi was unpacking the birthday feast that her grandmother made for “the Nam Do San in the old days” that Jip Yeong suddenly remembers why he wrote that birthday wish in his letter to her. All the young Jip Yeong wanted was to play Go-Stop with his whole family. A simple wish, but a big one for an orphan like Jip Yeong.

As Dal Mi said when Chul San asked why playing Go-Stop would be anyone’s wish:

“To someone, it might have a special meaning. What’s ordinary to one person can be extraordinary to another. He probably has fond memories of it. Maybe he really enjoyed playing it with his family on the holidays. Or maybe it wasn’t ordinary at all to him and made him envious.”

‘Thank you, Good Boy’

What we’ve seen throughout this series is how Jip Yeong truly has a heart of gold, despite his insistence that he’s not a “Good Boy” and his gruff and cynical exterior. In fact, he doesn’t understand why Ms. Choi keeps thanking him.

It’s his actual birthday, but he spends it trying to make Dal Mi happy. In a very real sense, he has already repaid his debt to Ms. Choi. Yet here he is, still unwilling to disappoint Dal Mi, or let her get hurt. It’s quite obvious that he’s developing feelings for her, even though he refuses to acknowledge it. And even Do San realizes it.

For his part, Do San is also experiencing his own heartbreak. When he takes her home, he asks Dal Mi what are the things that she likes about him. Unfortunately, everything she says she likes about him are not really him, but Jip Yeong as “Nam Do San”. Except for his big hands.

“Start-Up” Episode 4 is another example of this charming K-drama bringing its A game, effortlessly making us feel a whole range of emotions.

And reminding us once again that the simplest things may turn out to be the most important, and that we should never take even the most ordinary things for granted.

Start watching “Start-Up” now.

Previous reviews:

• ‘Start-Up’: Strong start as K-drama takes on tech startups
• ‘Start-Up’ Episode 2 review: Too good to be true?
• ‘Start-Up’ Episode 3: Sail off without a map