Does Jiro like Kluke in the game

Yes. It's implied throughout disc 1 and disc 2 of the first game. During an even in Pachess Town, Jiro even admits to Shu that he "really likes" Kluke. Here's the script:

Jiro: I'm going to save Kluke no matter what.
Shu: You sure have been acting strange lately. Whenever we talk about Kluke, you get all weird on me.
Jiro: It's because... I really like Kluke.
Shu: Uh... what... did you say...?

Another example is if the player speaks to one of Marumaro's brothers after the "medicine incident" in Lago Village. The sibling tells the group a magic word ("yourecharmbeautimiful") that will make girls like them. He concludes with a "Try it on someone you like". Jiro, not knowing that Kluke's listening, says "Hmm... I think I'll use that one." Kluke responds with a "Jiro, do you like someone?"

So that about sums it up. However, it's a bit unclear if Kluke likes Jiro just as much as he likes. Though a few of her responses in certain events (Lago Village events) hints that she may be a bit romantically interested in Jiro.