I Am Not A Goblin Slayer

Arriving in a fantasy Otherworld, Gauss obtains an Adventurer's Handbook that grows stronger the more monsters he slays and collects. Gauss originally thought he was embarking on a classic adventure to defeat the Giant Dragon, kill the Devil, and save the kingdom. Yet, seeing goblins breeding like pests and multiplying endlessly, along with the fast-growing kill count and rewards in the Monster Atlas, his face grows increasingly helpless...
"You have slain 1000 goblins! Intelligence +1, Strength +1, Constitution +1."
"The title 'Goblin Slayer' has upgraded to 'Goblin Expert'. You are an expert on goblins; few know better than you how to kill them."
"..."
"The title 'Goblin Expert' has upgraded to 'Goblin Star Destruction'. "